AP Computer Science Principles

Terabyte (TB)

1,024 gigabytes

Megabyte (MB)

1,024 kilobytes

Gigabyte (GB)

1,024 megabytes

Petabyte (PB)

1,024 terabytes

Kilobyte (KB)

1024 bytes

Lossy

A compression scheme in which "useless" or less-than-totally-necessary information is thrown out in order to reduce the size of the data. The eliminated data is unrecoverable.

Lossless

A compression scheme in which every bit of the original data can be recovered from the compressed file.

Aggregation

A computation in which rows from a data set are grouped together and used to compute a single value of more significant meaning or measurement. Common aggregations include: Average, Count, Sum, Max, Median, etc.

Bit

A contraction of "Binary Digit". A bit is the single unit of information in a computer, typically represented as a 0 or a 1

README

A document providing background information about a dataset.

Innovation

A novel or improved idea, device, product, etc. or the development thereof

Hexadecimal Number System

A number system consisting of 16 distinct symbols — 0-9 and A-F — which can occur in each place value.

For Loop

A particular kind of looping construct provided in many languages. Typically, a for loop defines a counting variable that is checked and incremented on each iteration in order to loop a specific number of times.

Function

A piece of code that you can easily call over and over again.

Open Access

A policy that allows people to have read access to things, e.g., libraries or online data

Algorithm

A precise sequence of instructions for processes that can be executed by a computer

Computationally Hard Problem

A problem that can not be solved in a reasonable amount of time. Heuristics are often used to create an approximate or good enough solution.

Undecidable

A problem that is so difficult, we can't ever create an algorithm that would be able to answer yes or no for all inputs, like determining if a user's program run on some input would always stop and not run forever

Hypothesis

A proposed explanation for some phenomenon used as the basis for further investigation.

Peer-to-peer networks

A system where one user's computer connects through the Internet to another user's computer without going through an intermediary "centralized" computer to manage the connection

Summary table

A table of aggregate information about a dataset (e.g., the average, sum, count of some values).

Image

A type of data used for graphics or pictures.

Crowdsourcing

Asking lots of users online to help with something, like funding a project, or running SETI@Home to help look for extraterrestrial signals

#000000

Black represented RGB in 32Bit Hex

#0000FF

Blue represented RGB in 32Bit Hex

Search Trends

Comparison of the popularity of topical queries in an online search engine as they relate to time.

Lossless

Compressing data in a way that preserves all data away and allows full recovery of the original, good compression -- usually not as good as lossy, like PNG images

Lossy

Compressing data in a way that throws some data away and makes it almost impossible to recover the original, great compression, like JPEG images

Metadata

Data that describes other data. For example, a digital image my include metadata that describe the size of the image, number of colors, or resolution.

Overflow

error that results when the number of bits is not enough to hold the number, like a car's odometer "rolling over"

Pivot Table

The name of the tool used by most spreadsheet programs to create a summary table.

BIN: 1110

The number 14

HEX: F

The number 15

Raw data

The original data as it was collected.

penRGB(255,255,255)

White

#FFFFFF

White represented RGB in 32Bit Hex

RBG Intensities

a 256-range (or 8-bit range) of values from light to dark on each of the three color channels (R,G,B)

Selection

a boolean condition to determine which of two algorithmic paths are taken, aka if-then

Big Data

a broad term for datasets so large or complex that traditional data processing applications are inadequate.

Library

a collection of commands / functions, typically with a shared purpose

API

a collection of commands made available to a programmer

.txt

a computer format that is structured as a sequence of lines of electronic text.

Documentation

a description of the behavior of a command, function, library, API, etc.

modulo

a mathematical operation that returns the remainder after integer division.

Round-off

error that results when the number of bits is not enough to represent the actual number, like 3 digits to represent π as 3.14

Data compression

involves encoding information using fewer bits than the original representation

DNS Server

is a hierarchical decentralized naming system for computers, services, or other resources connected to the Internet or a private network.

Cloud services

is a type of Internet-based computing that provides shared computer processing resources and data to computers and other devices on demand

IP addresses

is an identifier assigned to each computer and other device (e.g., printer, router, mobile device, etc.) connected to a TCP/IP network[1] that is used to locate and identify the node in communications with other nodes on the network

Public key encryption

is any cryptographic system that uses pairs of keys: public keys which may be disseminated widely, and private keys which are known only to the owner.

Phishing

is the attempt to obtain sensitive information such as usernames, passwords, and credit card details (and, indirectly, money), often for malicious reasons, by disguising as a trustworthy entity in an electronic communication.

Reasonable time

polynomial in the number of steps an algorithm takes in the worst case based on the input size

Malware attacks

short for malicious software, is any software used to disrupt computer or mobile operations, gather sensitive information, gain access to private computer systems, or display unwanted advertising

Byte

technical term for 8 bits of data

RGB

the color model that uses varying intensities of (R)ed, (G)reen, and (B)lue light added together in order to reproduce a broad array of colors.

TCP/IP network

the conceptual model and set of communications protocols used on the Internet and similar computer networks. It is commonly known as TCP/IP because the original protocols in the suite are the Transmission Control Protocol (TCP) and the Internet Protocol (IP).

file extensions

the endings of file names that indicate to the computer the format for how the underlying bits are organized.

Cipher

the generic term for a technique (or algorithm) that performs encryption

Digital Divide

the gulf between those who have ready access to computers and the Internet, and those who do not.

Moore's Law

the observation that computing power roughly doubles every two years.

Filter

tool/technique using dynamic parameters for reducing a data set to viewing only similar items in a row or column.

asymmetric encryption

used in public key encryption, it is scheme in which the key to encrypt data is different from the key to decrypt.

Heuristic

using a "rule" to guide an algorithm, like always walking toward the north star if you were stuck in a forest

Iteration

using a looping control structure, like while, for, foreach, repeat, repeat-until, etc.

Vigenère cipher

a method of encrypting text by applying a series of alphabetical shifts based on the letters of a keyword.

Heuristic

a problem solving approach (algorithm) to find a satisfactory solution where finding an optimal or exact solution is impractical or impossible.

Encryption

a process of encoding messages to keep them secret, so only "authorized" parties can read it.

Decryption

a process that reverses encryption, taking a secret message and reproducing the original plain text

Caesar Cipher

a technique for encryption that shifts the alphabet by some number of characters

.zip

an archive file format that supports lossless data compression; may contain one or more files or directories.

.mp3

an audio coding format for digital audio which uses a form of lossy data compression which works by reducing (or approximating) certain components of the audio that are considered to be beyond audible human hearing.

Random Substitution Cipher

an encryption technique that maps each letter of the alphabet to a chosen other letters of the alphabet.

Domain names

an identification string that defines a realm of administrative autonomy, authority or control within the Internet.

Sequencing

code flows line by line, one after another, like a recipe

Metadata

data about data, like a camera storing the location, aperture, shutter speed, etc. for a digital photo

#FF0000

Red represented RGB in 32Bit Hex

.png

(Portable Network Graphics) a raster graphics file format that supports lossless data compression.

.wav

(Waveform Audio File Format) an audio coding format standard for storing an audio bitstream of uncompressed audio data.

.gif

(acronym for Graphics Interchange Format) a bitmap image format which uses the LZW lossless data compression technique to reduce the file size without degrading the visual quality. Supports 8 bits per pixel for each image and animations.

.jpg or .jpeg

(acronym for Joint Photographic Experts Group), a commonly used lossy compression format for digital images, particularly for those images produced by digital photography. The format supports adjustable degrees of compression.

.bmp

(bitmap image file or bitmap) is a raster graphics image file format used to store digital images.

CSV

Abbreviation of "comma-separated values," this is a widely-used format for storing data.

Creative Commons

An alternative to copyright that allows people to declare how they want their artistic creations to be shared, remixed, used in noncommercial contexts, and how the policy should propagate with remixed versions

Parameter

An extra piece of information that you pass to the function to customize it for a specific need

APIs

Application Programming Interface, how you define libraries and call them

Linear vs binary search

Going one by one vs starting in the middle and going left/right like looking for a word in the dictionary -- binary search requires the list to be sorted in order

#00FF00

Green represented RGB in 32Bit Hex

Visualization

Images, diagrams, tables, etc created from information extracted from a given data set, with the express intention of highlighting a data story.

Intellectual property

Intellectual property (IP) refers to creations of the mind, such as inventions; literary and artistic works; designs; and symbols, names and images used in commerce.

Citizen Science

Lots of people to help with a scientific project, like asking everyone around the world to count the butterflies they see one day

Abstraction

Pulling out specific differences to make one solution work for multiple problems.

Pixel

Short for "picture element" it is the fundamental unit of a digital image, typically a tiny square or dot which contains a single point of color of a larger image.

Moore's Law

The # of transistors on a chip doubles every two years

DDos Attack

denial-of-service attack (DoS attack) is a cyber-attack where the perpetrator seeks to make a machine or network resource unavailable to its intended users by temporarily or indefinitely disrupting services of a host connected to the Internet.

Loop

The action of doing something over and over again.

Digital divide

The idea that some communities / populations have less access to computing than others

Public Key Encryption

Used prevalently on the web, it allows for secure messages to be sent between parties without having to agree on, or share, a secret key. It uses an asymmetric encryption scheme in which the encryption key is made public, but the decryption key is kept private.

Cloud Computing

Using distributed calculations and/or storage for big data or a web applicatio)

Not reasonable time

Usually exponential in the number of steps, like doubling every time your input grows by one

Cracking encryption

When you attempt to decode a secret message without knowing all the specifics of the cipher.