Computer Science (Final)

Three common categories of e-commerce

1. Business-to-consumer (B2C): A company (like Amazon) sells goods/services directly to people. B2C is likely the best-known e-commerce category. 2. Consumer-to-consumer (C2C): A company (like eBay) enables people to sell goods/services to each other. - C2C is likely the second best-known e-commerce category. 3. Business-to-business (B2B): A business sells goods/services to another business.

Distributed DoS

A DoS attack using multiple (distributed) computers - DoS attacks are commonly accomplished by instructing multiple infected computers that are part of a botnet to simultaneously access the target website.

Security Breach

A case of unauthorized computer access. Some examples of security breaches include: • A person's private email and photos being viewed by someone without permission. • A person's email or social media account being used by someone else to post inappropriate messages. • A computer having a hidden program installed that sends "spam" emails without the computer owner's knowledge. • An organization's confidential customer and financial data being accessed by a competitor. • An organization's customer credit card data being copied and sold. • An organization's servers being maliciously shut down, such as shutting down a government or company website. • Confidential data from a computer being posted publicly to harm or embarrass a person or organization. - As people and companies use computers for more personal and business activities, the impact of security breaches increases, as does the lure of breaching security. - An individual may suffer tremendous trouble, stress, and financial loss if a personal computer or company account is compromised. - A single person can now inflict much greater harm on a company via hacking than in the past. - Countries increasingly spy on and conduct warfare against other countries not via physical force but rather via computer. - Computer security professionals are thus in increasing demand.

Outsourcing

A common business term referring to company A using company B to do work that might otherwise have been done by the company A's employees. - Improvements in telephone communications and computers have made outsourcing easier, leading to many companies outsourcing work, often to people in other countries where labor is cheaper. - Commonly outsourced work includes customer support, accounting, tax preparation, software development, training material development, or manufacturing. - Outsourcing has grown significantly since the 1980s, though many companies are reducing outsourcing due to poor quality stemming from difficulties relating to separated teams and miscommunications.

Account Security

A common security breach involves unauthorized access to a person's online account, such as an email account or Amazon account. - Such breaches can occur: • If a person leaves a computer unattended without signing out, especially a public computer like in a school lab or hotel lobby. • If a person saved a password on a public computer. • If a person's computer is stolen and email was left signed in or the password was saved. • If a hacker obtains or guesses a user's password. - Signing out regularly, changing passwords frequently, never writing a password (in a file, email, or paper), using different passwords for different sites, and using hard-to-guess passwords can improve account security. - If a user must write something, a user might write a hint to help remember the password.

Compromised

A computer that is hacked is said to be __________

Infected

A computer with a virus is said to be ______ - A computer virus' purpose may include: • Using the computer for illicit tasks (discussed below) • Stealing information from the computer, like credit card numbers or passwords • Doing harm, like deleting data (least common) - A computer may show little or no sign of being infected. One clue is that the computer may be slower than usual, or is active even when not in use.

Internet Scam

A dishonest scheme or fraud using the Internet. - The Internet has been filled with scams since the Internet's rise in the 1990's. - Internet scams cost individuals and companies hundreds of billions of dollars per year. - A wise Internet user keeps a careful watch out for scams.

Hack

A malicious security breach done by unauthorized access - The most common form of a breach. - Other breaches may be caused by system glitches or by human error

419 scam (or Nigerian scam)

A particular scam where the scammer establishes contact with an individual to help with a business transaction like transferring money out of a country, for which the individual will supposedly receive a large payment. - These scams are sometimes called Nigerian scams due to a famous scam email involving a supposed Nigerian prince, or 419 scams due to the Nigerian criminal code number dealing with fraud. - While many such scams may have originated in Nigeria, many have nothing to do with Nigeria.

Antivirus Software

A program that looks for known viruses and strives to disable found viruses, by searching a hard drive, and/or by monitoring visited websites and downloaded files. - Some company websites, like drive.google.com, check for viruses on the server before providing a file for download. - Antivirus software is rare for smartphones and tablets (and in 2015 iOS disallowed most supposed antivirus apps).

Computer Virus

A program that runs on a user's computer without permission, and spreads itself to other computers, often via email - Attaches itself to other programs and is self-replicating - The most common way for a virus to spread is via email, where a user is tricked into downloading and running an application that installs a virus. - However, some viruses can be received by visiting particular websites, either by downloading items from such sites, or sometimes merely by visiting the site. - Sites that host free games, that support illegal free music/video downloads, that provide gambling, or that provide free pornography, commonly exist for the purpose of spreading viruses. - Some viruses also use peer-to-peer file transfers (commonly used for illegal video/music sharing) to spread. - Tens of thousands of known viruses exist, with hundreds discovered each month. - With a bad virus infection, a user may have to wipe the computer's drive and reinstall the operating system and programs. - Smartphones and tablets tend to have fewer viruses due to having newer OS'es designed for security, and to having most applications being checked for viruses before being available. - A virus commonly has the infected computer do illicit tasks, such as send spam email--another common illicit task is attack an organization's website (DoS)

Crowdsourcing

A term that developed with the web, referring to getting work done via a community of web users (the "crowd"). - The term is a combination of crowd and outsourcing. - Crowdsourcing usually (but not always) relies on free contributions by the crowd. - Perhaps the best-known crowdsourced product is Wikipedia, where users produce encyclopedia articles, in contrast to a company paying contributors of articles. - Another is Yelp, where users produce reviews of restaurants and other establishments. - Creative crowdsourcing ideas continue to launch new businesses, many of which disrupt established industries.

Digital Footprint

A user on the Internet leaves electronic footprints. - A user's information footprint is not just what the user intentionally posts online. - The footprint consists of all of the information that a user posts or that others post about the user, the hidden data attached to those posts by the services used, the record of a user's online activities, and also the inferences that can be drawn from putting that collective information together. - A good practice is thus to periodically check and update privacy settings, if possible, to limit unintentional information sharing.

Online is real

A user's online activities and communications can have the same impact as a user's offline activities and communications. - A good practice is to share information as if the information is public and would be interpreted in the worst possible way. - Many users think of the Internet as a separate world, and assume online identities, actions, and relationships are somehow separate from the "real-world". - Individually-operated technologies used to access the Internet promote an illusion of separation between the online world and the real world.

Phishing

An Internet scam that baits a user to share sensitive information like a password or credit card number. - The word derives from "fishing", where one puts out bait and hopes a fish will bite. - The most common phishing approach sends email to a user, appearing to legitimately be from a known organization like PayPal, Amazon, Bank of America, UPS, the government, or a person's own employer. - Modern email systems like Gmail or Yahoo filter most such email directly to a spam folder, but some spam emails occasionally get through. - A wise Internet user rarely clicks on links provided in emails; a concerned user might instead sign directly into the bank website, without clicking on the link. - If clicking on a link in an email, a wise Internet user looks carefully at the real URL first (e.g., by hovering a mouse over the link and viewing the target link, without clicking).

Craigslist Scam

An Internet scam where a seller receives an email from a buyer offering to buy an item. - The buyer pays by check (or money order) and requests immediate shipment of the item. - The seller deposits the check and sends the item, but in a few weeks the seller is notified of insufficient funds to cover the check. - The seller has no means to get back the sent item.

Data Mining

An advanced technique that can analyze language usage, faces, locations, and other items to match a unique individual. - It is the computational process of discovering patterns in large data sets ("big data") involving methods at the intersection of artificial intelligence, machine learning, statistics, and database systems. - The overall goal of the data mining process is to extract information from a data set and transform it into an understandable structure for further use.

Security Hole (Vulnerability)

An aspect of a computer that can be used to breach security. - Security holes commonly exist in operating systems. - Once discovered, OS makers update the OS to close such holes. - Thus, computer users are advised to keep their OS'es up-to-date, not only to gain new features, but to close security holes. - Many modern OS'es (Windows, MacOS, iOS, Android) let a user know an update is available, or allow the user to check for updates from a menu option.

Strategies to protect privacy as searching capabilities improve.

Assume information will be available - Assume information will eventually be searchable and findable — even if the techniques aren't available today. Stay informed - When they appear, read news stories about what kind of information can be made public. Keep in mind policies may change in the future. • Periodically check privacy settings for any app used. • Users should search regularly to see what information regarding the user is available for others to see. Choose apps used - Only provide as much personal information as is needed. • Always assume information will become findable later. • Before providing information in a form — online or even paper — consider what the information is needed for.

Being Anonymous

Being anonymous on the Internet is nearly impossible. - Even "private browsing" or "incognito" modes on web browsers still may transmit such information. - Advanced users who use an anonymization proxy to cover the IP address may still have uniquely identifiable information leak through, such as a browser configuration, cookies, or the information the user submits upon request.

Craigslist

Craigslist is another C2C e-commerce company, started in 1995 by Craig Newmark in San Francisco as an email list for friends of items for sale, now allowing users to sell goods/services to one another, replacing what used to be known as newspaper "classified" ads. - Products are mostly local in-person pick ups for hard-to-ship items like furniture or vehicles - Has more emphasis on local services like handymen, house cleaners, etc. - While widely used and well known, Craigslist seeks relatively modest revenues, obtained from small fees for certain kinds of listings like job listings, and in some regions listing for apartments or cars/trucks; most listings are free, and the site posts no advertisements.

Strategies to minimize a user's information footprint.

Customize the technology - Check privacy settings on mobile apps, computer software, and online accounts. Settings that can typically be turned off: • Location services, which provide GPS information about current location • Metadata in images • Sharing contact information with third parties Communicate about preferences - Check privacy status with companies. Banks, insurance providers, hospitals, and other companies are often legally bound to let users opt out of at least some types of data sharing. Choose apps used - Delete online accounts not in use and remove content that is no longer needed.

Strategies to protect a user's identity

Customize the technology - Use privacy tools such as Ghostery, Disconnect, or Privacy Badger to limit a websites' ability to track user activities. Choose apps used - Only provide as much personal information as is needed. • Always assume there is no anonymity, and therefore less privacy, when doing something electronically. • Before providing information in a form — online or even paper — consider what the information is needed for.

Defenses Against DoS

Defenses against DoS attacks include detecting sources (like IP addresses) that are generating the attack, and blocking requests from those sources before those sources' requests reach the server, such as blocking at a router. - Companies may also contact law enforcement (the FBI in the U.S.) to try to track down the perpetrator. - Law enforcement sometimes does track down the perpetrator

Encrypting Keys (email)

Email messages could potentially be viewed as they travel through the Internet. - Programs exist to encrypt email messages before sending, resulting in unreadable text, and requiring use of special codes known as keys to decrypt the message. - Email encryption programs are not particularly easy to use and thus have not seen wide usage, but are popular among people with heightened security awareness/concerns.

Phishing Emails

Fraudulently ask users to provide sensitive account information by posing as legitimate companies.

Guide to Reduce Problems

Having: • The top of the screen just below eye level • Head and neck balanced and in line with the torso (no hunching over) • Wrist and hands in-line with forearms - In addition to the setup, guidelines suggest taking frequent small breaks ("micro" breaks), and changing tasks frequently, to avoid long periods of repetitive motion like typing. - Furthermore, due to the sitting complications mentioned above, new guidelines recommend standing at least every half hour for 2-3 minutes, and even spending some time working at a standing desk. - Research shows that computer use and TV watching by kids can impact brain development, leading to later hyperactivity, attention issues, and even more likelihood for committing crimes. - Research is ongoing, but parents may do well to seriously consider whether kids should be spending significant time in front of a screen, versus interacting with other people, playing with physical items, being outdoors, etc. - The impact of computer use on adult brains is also an area of active research, with many concerns.

Two-step Verification

Helps secure a user's account by requiring the user during sign in to enter a temporary code appearing on the user's mobile phone, which the user usually carries. - A password thief who tries to sign in on a different computer will not know the code. - Also, some accounts allow a user to provide a backup access means, such as another email address or a mobile phone number. Thus, if a password is forgotten, or illegitimately changed, the user might still be able to regain access to the account.

Information Sharing

Information is recorded as users interact on the Internet. - Once information is shared, users cannot "unshare" the information. - A good practice is to think twice before sharing any information online. • Information can be replicated - Websites are crawled, analyzed, and cached by search engines. Automatically backing up or mirroring information is a common practice. Other users frequently repost (retweeting, etc.) social-media content and forward email and text messages. • Information can be made public - Secure data storage can be compromised; user accounts could be hacked or the employees of a service can access user data from the back end. Private data from cell phones, email accounts, and computer hard drives can be subpoenaed and used in court. • Information can be sold - Websites' privacy settings and copyright terms often change. Websites can collect and sell user information to other businesses. • Information can be manipulated or misinterpreted - Messages may be taken out of context and are often missing cues that convey the user's intent. Information may be shared with others who are not intended as the target audience, and may interpret the information according to their own expectations and viewpoints.

Cryptography

Involves converting a message into an unreadable form (encryption) and converting that message back into a readable form (decryption), using secret conversion techniques that only the sender and intended receiver know. - Some websites must be accessed using https rather than http, which uses cryptography to carry out secure (hence the "s" in https) transmissions.

Denial of Service

Is achieved by submitting huge numbers of access requests simultaneously to one website, which overloads that site's web server, thus preventing legitimate requests from being handled (those requests are denied service). - Infected computers are commonly used to carry out DoS attacks. - A denial of service (DoS) attack is achieved by submitting huge numbers of access requests simultaneously to one target website, causing that site's web server to be overloaded, thus preventing legitimate requests from being handled (those requests are "denied service"). - A DoS attack may be used to try to hurt a company's business, to hassle an organization, to express dissatisfaction with a government, etc. - DoS attacks are of course illegal in most countries.

Tips for effective email communications.

Keep short - Many people don't read long emails, so the time taken writing lengthy emails is often wasted, and key points may be overlooked. Put key points first - Key points buried inside an email are more likely to be overlooked. Writing like a newspaper article may help, with key points in the subject and the first sentence or paragraph. Think about recipients - People are often unintentionally omitted (such as when using Reply instead of Reply All), or unnecessarily included (such as when using Reply All when the reply only relates to one person). Also, care must be taken to ensure the original sender would approve of an email being forwarded or to having a person added to the cc list. Keep threads separate - Multiple points buried inside an email are more likely to be overlooked and are harder to find in one's archived email later on. A new email thread should be created for each point and include a descriptive subject. Check spelling - The neatness of an email reflects on a person similarly to how the neatness of one's clothing and hair does. Spelling, grammar, and formatting all matter. Don't email angry - One might wait a few hours, or overnight, to decide if the email really needs to be sent Assume public - Email may be permanently stored on a server. A disgruntled employee or a hacker might make emails public. Thus, sensitive discussions may be better done verbally. Be careful with humor - Jokes can be easily misconstrued, due to lack of body/facial cues, or lack of context (as when read out of context of a series of humorous email exchanges).

Regulating Spam

Many countries have laws that regulate spam. • For example, the U.S.'s federal law known as CAN-SPAM allows unsolicited marketing email but requires such email to have an unsubscribe mechanism. - Religious and political messages are exempt, as are companies having an existing relationship with a person. - Many reputable companies follow that law's rules, but many spammers do not, and violations of the law are rarely pursued by the U.S. law enforcement.

Illegitimate User

May do various illicit things, such as read personal messages and view private photos; obtain valuable information contained in emails like account numbers, passwords, confidential plans, or home addresses; access contact lists; post inappropriate items on other sites using that email; or post a person's private emails publicly to embarrass or harm the person. - The illegitimate user might change the password and thus assume control of the account, and then use the account for various illicit tasks. - Or the illegitimate user might quietly sign in regularly without the legitimate person knowing.

Employers

More than 40 percent of employers use social-media and search engines to research job candidates. - Online activities are increasingly used to make real-world decisions. • For example, many employers will review a potential employee's social-media content before making a hiring decision. - Connection between contexts is not unique to the Internet; a users' school or work lives are connected to their social lives. - Users may be judged in one context based on how the user behaves in another context. However, the way information persists and is replicated on the Internet adds a new dimension. - Once information about a user is shared online, that information persists and becomes part of how a user is judged by others.

Public-key Cryptography

Often, a sender and receiver don't already share a secret key, and the key of course can't just be sent over the Internet unencrypted since an eavesdropper could then know the key. - Public-key uses two keys: A public key the sender uses to create encrypted messages, and a mathematically-related private key that the receiver can use to decrypt messages encrypted by that public key. - Is convenient due to not requiring a single shared secret key between sender and receiver, but requires more computation during encryption/decryption due to being mathematically more complex

Amazon

One of the best-known B2C e-commerce companies, started in 1994 as an online book seller, but today selling a vast array of products to consumers. - Today, Amazon also sells video-on-demand, electronic book readers, and more. - 2014 revenues were nearly $100 billion. - Most brick-and-mortar B2C companies have an e-commerce presence, such as target.com, walmart.com, costco.com, etc.

Email Inconvenience

People don't want to type a password for every sign in, or remember to delete private emails when no longer needed. - Furthermore, no security is perfect. And, sometimes emails are legally accessible by companies, governments (as in a court case), etc. - Recognizing that email is hard to secure, many seasoned computer users provide this advice: • Don't put anything in an email you wouldn't want made public. • Instead, people may use phone or in-person discussions to share more-sensitive information.

Deleting Information

Protocol do not exist for the automatic deletion of data. - Even with a large number of resources, a user cannot track all digital and physical copies of a piece of information. - Apps often backup and archive data. - Online archival repostories (example) copy and store information indefinitely. - Information that seems to have been deleted, like Snapchat photos, may still be retrieved by users with the right technical skills. - Even if the original data were somehow all deleted, information derived from data mining and inference techniques could still persist. - The only way to guarantee control over sensitive information is not to share the information.

Encryption

Scrambles plaintext into a cyphertext to prevent unauthorized users from accessing the information. - Encryption is similar to writing a postcard using a secret code language, so that the information is not readable along the delivery route. - While privacy and security are two different concepts, without security there is no privacy. - Users in the same secure wireless network have the same decryption authorization for that network. - Additional encryption may be needed to hide information from other local users. - Multiple layers of encryption can improve the security of communications. - Encryption cannot guarantee security, but stronger encryption does make information harder to access. -The encryption "strength" is determined by a number of factors including the type of encryption algorithm used and the size of the cryptographic key. - The stronger the encryption, the more computing resources are needed to break the encryption and access the user information.

Deep Searching

Search engines are able to perform "deeper" searching of more types of data as search techniques continue to improve. - Semantic searching techniques, such as inferring the context of a term from other terms in a search, help search engines to better understand the user's intended query. - Search engines are able to extract data from text, images, video, and audio, then connect the data into meaningful results. - The amount of information on the Internet continues to grow with the availability of Internet-connected devices, services, and applications. - Users regularly share information from their daily lives through social-media apps. - Information previously only available offline is now available online due in part to records being scanned and made searchable. - Information that may not be retrievable today may be retrievable tomorrow due to changes in terms of service, public policy, law, and technical privacy settings. - A good practice is to actively monitor a user's information footprint.

Hacktivism

Some attacks can be politically motivated - Hacktivism is the use of computer networks to promote a social or political cause. - A smaller number of DoS attacks are motivated by the "thrill" of disrupting popular websites and services.

Spammers Make Money

Spammers make money in various ways. • One way is through referrals: A referrer sets up an account with a legitimate business like an online pharmacy, and then refers customers to an account-specific URL at that business (like http://somebusiness.aaa.zzz/account555); the business gives the referrer a percentage of sales. The spammer uses spam to try to refer customers to that • A spammer may operate a business, like a porn site or gambling site, and attracts customers directly via spam. Customers pay a fee to access the site. • Another way is through botnets; the spammer spreads a virus to gain control of thousands of computers, and then rents usage of those computers to others (typically for malicious purposes like denial-of-service attacks or sending more spam). - Spam has low success rates but can still be profitable for spammers. - Most spam is filtered by spam filters, and spam that gets through is usually ignored. But, spam is nearly free to send, so spammers can send millions of emails a day. - If just a handful of those emails result in sales, the spammer has still made money.

Rapleaf.com or Data.com

That aggregate data from many sources to yield a full personal profile, which can include home address, income level, job description, and other private information. - Even a single link between an online identity and a person's real self can lead to people discovering a user's identify.

E-commerce (electronic commerce)

The conducting of business transactions on the web. E-commerce companies are often contrasted with brick-and-mortar companies that do business in physical stores. - E-commerce continues to grow. E-commerce is also eating up an increasingly larger percentage of brick-and-mortar store sales. - Many businesses are seeing significant reductions of sales due to e-commerce competitors like Amazon, such as Sears (general goods and clothing), Barnes and Noble (books), and Staples (office supplies). Some have gone out of business, such as Circuit City (consumer electronics).

Computer Security

The prevention of unauthorized computer access, including viewing, changing, or destroying a computer or data.

Communication Protocol

The rules for transferring information among computers, often includes encryption.

Ergonomics

The science of designing things for easy safe use by people. - While using computers may seem safer than using other kinds of equipment, computer use has the potential for causing physical harm

Symmetric-key Cryptography

The sender and receiver use the same key for encryption and decryption (symmetric refers to both sides being the same, in this case the sender and receiver keys both being the same). • Ex: Given message "Hello", a simple encryption approach might shift each letter forward in the alphabet by some number of places. So a key of 2 would encrypt "Hello" to "Jgnnq" because J is 2 letters after H, g is 2 after e, etc. To decrypt, the receiver shifts each letter backward using the same key as the sender, in this case 2. - Real cryptography uses sophisticated math techniques (not just letter shifting) and huge keys like 1099511627776 (not just 2).

Strategies to contain personal information on the Internet.

Think before posting - Be cautious of whom information is shared with. • Information shared on the Internet can be duplicated. Users do not have control over the duplicated information or the ability to erase the information. • Consider how the information will be interpreted by others who may not be the intended target audience. • Consider how a user's interests might change over time. Check app settings - The default privacy settings on many apps is to share every type of information with the widest audience possible. • Limit sharing by update settings to "opt out". • Consider which groups of people information is shared with — then set sharing to include only those groups. Communicate about preferences - Check privacy status with companies. Banks, insurance providers, hospitals, and other companies are often legally bound to let users opt out of at least some types of data sharing.

Strategies to minimize negative consequences of online behavior.

Think before posting - Consider how the information may affect the user and others within the user's social circle. • Formulate posts as positively as possible • Keep in mind that information is easily misinterpreted Get the facts - Check the source of the information before repeating or reacting to the information. Communicate about preferences - Communicate: • Get consent before sharing information about others • Communicate preferences about the types of information others should (or should not) share Check app settings - The default privacy settings on many apps is to share every type of information with the widest audience possible. • Limit sharing by updating settings to "opt out" • Consider which groups of people information is shared with — then set sharing to include only those groups

Good Passwords

Typically are not words in the dictionary - May mix letters, numbers, and special characters like !, @, $, and %.

Security

Typically, the most important security problem is due to human behavior. - Security can be compromised by users because of weak passwords, because passwords are stored in insecure places (physical or virtual), or through social engineering like fake "phishing" emails.

Malware (short for "malicious software")

Undesired software that is typically installed without a user's knowledge and typically bad for the computer or user. - A virus is one type of malware. - The objective of malware includes doing damage, selling products, spying, and more. - Malware is common in desktop and server machines - Malware is less common in smartphones and tablets, for reasons including: (1) Having newer OS'es created with security in mind from day one, and (2) Controlling how apps are installed using an "app store" where applications must first be approved, such approval including checking for malicious code. • A smartphone/tablet user who only downloads apps from the device's official app store typically has almost no malware issues.

Spam

Unsolicited mass email, perhaps advertising prescription drugs for sale, or further spreading the virus. - Spamming is illegal in many countries. - If a spammer sent millions of emails from one computer, email companies might block that computer, and authorities might find the spammer. - Instead, a spammer instructs thousands of infected computers to send the spam emails. - Spam is unwanted mass-sent email. - Most spam advertises products or sites (often porn sites). - Some (about 5%) is used for phishing or spreading malware (like viruses). - Because spam costs the sender almost nothing, spam has grown tremendously, making up 50%-80% of all Internet email traffic in 2014.

Types of Malware

Virus - A software virus is malware that spreads itself via attachment to a host file, like a biological virus attaches to a human. Worm - A software worm is malware that spreads itself without using a host file. Trojan - A software trojan (or trojan horse) is malware that a user installs believing the software to be legitimate, but the software actually has a malicious purpose. Adware - Adware is malware that displays advertisements to the user, commonly in a web browser. Spyware - Spyware is malware that collects information from a computer without the user's knowledge.

Common protocols involving encryption

Wi-Fi - WPA2 (Wi-Fi Protected Access II) - WPA (Wi-Fi Protected Access) - WEP (Wired Equivalent Privacy) Email - PGP (Pretty Good Privacy) - SSL (Secure Sockets Layer) Web - HTTPS (HyperText Transfer Protocol Secure) File transfer - SFTP (Secure File Transfer Protocol)

Examples of Crowdsourcing

Wikipedia - Online encyclopedia. Users contribute/polish/expand articles. One of the most-visited websites in the world.\ Yelp / Trip Advisor - Reviews of restaurants, hotels, and more. Users contribute reviews of food, hotels, prices, etc., often including photos. Yelp started mostly with restaurants, and Trip Advisor with hotels, but both have expanded. Kickstarter - Crowdfunding. In crowdfunding, someone requests funding for a company, product, idea, cause, etc., and users choose to contribute. Individual contributions may be small, but a large number of contributors may add of up thousands or millions of dollars. Waze - Driving application. The basic app includes maps and turn-by-turn driving instructions. Users submit traffic and accident updates that get included on the map reCAPTCHA - Verification app. Users type in two words shown in a distorted manner, one word for verifying the user is a human (to prevent automated tools from creating accounts on websites), the other word to help digitize text (the user isn't told which is which). Several years of old editions of the New York Times, for example, have been digitized in this manner. Netflix Prize - Competition for best movie recommendation predictor. Netflix offered one million dollars to anyone who could improve on Netflix's movie recommendation algorithm by more than 10%. Thousands of teams submitted, and a team was awarded the prize in 2009. Khan Academy - Educational videos site. Khan Academy is relying on users to provide captions in various languages for the site's videos. Mechanical Turk - Human intelligence tasks. People post jobs requiring human intelligence, typically simple low-paying tasks, and users can bid to complete the tasks. Tasks might include choosing among two images for a website, recognizing the singer of a song or person in a photo, searching satellite photos for a missing ship, etc. Airbnb - Private housing for short-term rentals (hotel alternative). People post availability of rooms for rent in private homes. Uber / Lyft - Private transportation (taxi alternative). Drivers use their personal vehicles to provide rides. Users request a ride using a smartphone app, can see location of drivers, and can rate drivers (and drivers can rate passengers). Payment is automatically handled via the app. Bleacher Report - Sports news and analysis. Users could become writers and contribute news articles.

Computer Related Injuries

Wrist injuries: Repetitive typing can cause carpal tunnel syndrome, in which a nerve in the wrist becomes compressed, causing pain, numbness, and tingling in the hand, arm, or shoulder. Vision problems: Straining to view items that are small or have low resolution, and viewing things close to one's eyes for long periods, can lead to various eye problems. Back pain: Spending long periods in a hunched or other unnatural position while looking at a computer screen can cause problems with the back and neck, and may also cause headaches Sitting complications: Sitting for long periods at a computer can cause serious health problems such as high blood pressure, obesity, heart disease, and cancer. Such problems occur even if the person exercises regularly. The seated position itself is apparently the problem—a relatively new finding.

Key

a number (or text string) used to encrypt or decrypt messages.

brick-and-mortar

companies that do business in physical stores.

Ebay

eBay is one of the best-known C2C e-commerce companies, started in 1995 to support online auctioning mostly of used goods, but today selling new and used items in auction or non-auction format. - Products are mostly delivered via mail

The Cryptographic Key

is used by an algorithm to transform plaintext into ciphertext or ciphertext into plaintext.

Crowdsourcing Advantages

• Lower cost: Users often work for free. Reasons include desiring to contribute to society, seeking recognition, wanting social interactions, or simply enjoying the task. - Any pay is typically low due to competition. • Scale: The more users, the more work that can be done. Wikipedia and Yelp, for example, have far more articles/reviews, updated far more frequently, than any company could possibly produce with paid employees. • Quality: Crowdsourced products could potentially be of higher quality, due to having many people contributing, revising, and polishing a product. - Ex: A single paid reviewer of a restaurant may have a different opinion than typical people, whereas the average of 500 reviewers' ratings is more likely to match the typical - Quality can also be a disadvantage: Contributors with little knowledge or talent may produce poor products, or may have extreme bias. - Ex: Some Wikipedia articles or Yelp reviews may be hard to read, or may be inaccurate, as may happen when a restaurant owner submits a negative Yelp review of a competing restaurant.