Module 2 - Unit 1: Digital Content - Section A: Digital Basics

Bit

A bit is a 0 or 1 used in the digital representation of data. Even though the word bit is an abbreviation for binary digit, it can be further abbreviated, usually as a lowercase b. Transmission speeds are expressed in bits,

File

A digital file, usually referred to simply as a file, is a named collection of data that exists on a storage medium, such as a hard disk, CD, DVD, or flash drive. A file can contain data for a term paper, Web page, email message, or music video.

File Format

A file name extension, such as .mp3, can be appended to the end of the file name after a period. This extension indicates the file format; the type of data in the file and the way it is encoded.

File Name Extension

A file name extension, such as .mp3, can be appended to the end of the file name after a period. This extension indicates the file format; the type of data in the file and the way it is encoded.

Byte

A group of eight bits is called a byte and is usually abbreviated as an uppercase B. whereas storage space is expressed in bytes.

Binary

A traditional light switch is also binary because there are only two possible states.

ASCII

ASCII (American Standard Code for Information Interchange, pronounced "ASK ee") requires seven bits for each character. For example, the ASCII code for an uppercase A is 1000001. ASCII provides codes for 128 characters, including uppercase letters, lowercase letters, punctuation symbols, and numerals.

Analog Data

Analog data is represented using an infinite scale of values.

Character Data

Character data is composed of letters, symbols, and numerals that are not used in calculations.

Data

Data refers to the symbols that represent people, events, things, and ideas. Data can be a name, a number, the colors in a photograph, or the notes in a musical composition.

Data Representation

Data representation refers to the form in which data is stored, processed, and transmitted. Today, digital data representation has replaced the analog data previously used for storing and transmitting photos, videos, and text.

Digital Data

Digital data is text, numbers, graphics, sound, and video that have been converted into discrete digits such as 0s and 1s.

Extended ASCII

Extended ASCII is a superset of ASCII that uses eight bits for each character. For example, Extended ASCII represents the uppercase letter A as 01000001. Using eight bits instead of seven bits allows Extended ASCII to provide codes for 256 characters. The additional Extended ASCII characters include boxes and other graphical symbols.

Kilobit

For digital devices where base 2 is the norm, a kilo is precisely 1,024, or 2^(10). Kilobit (Kb or Kbit) can be used for slow data rates, such as a 56 Kbps (kilobits per second) dial-up connection.

Delimiter

Formatting codes can be added to documents directly within the text stream, using some sort of delimiter to signal the beginning and end of the formatting command. A delimiter is a special character used to separate commands or formatting characters from the rest of the text in a file. Slashes // and angle brackets < > are commonly used delimiters.

Gigabit

Giga is derived from 2^(30). Gigabit (Gb or Gbit) is used for really fast network speeds.

Gigabyte

Gigabyte (GB or GByte) is commonly used to refer to storage capacity.

Kilobyte

Kilobyte (KB or Kbyte) is often used when referring to the size of small computer files.

Lossless Compression

Lossless compression provides a way to compress data and reconstitute it into its original state. Character data and numeric data in documents and spreadsheets are compressed using lossless techniques so that the uncompressed data is exactly the same as the original data.

Lossy Compression

Lossy compression throws away some of the original data during the compression process. When the data is uncompressed, it is not exactly the same as the original. This type of compression is typically used for music, images, and videos because the human ear or eye cannot discern minor changes.

Megabit

Mega is derived from 2^(20). Megabit (Mb or Mbit) is used for faster data rates, such as a 25 Mbps (megabits per second) Internet connection.

Megabyte

Megabyte (MB or MByte) is typically used when referring to the size of files containing photos and videos.

Numeric Data

Numeric data consists of numbers that can be used in arithmetic operations. Digital devices represent numeric data using the binary number system, also called base 2.

OCR

OCR (optical character recognition) is a process that interprets individual characters during or after a scan. It assigns the appropriate ASCII code to each letter and outputs the document in a format that can be edited using word processing software. OCR software is available for most scanners and is handy when you have a printed copy of a document that you want to modify, but would prefer not to retype.

ASCII text

Plain, unformatted text is sometimes called ASCII text and is stored in a so-called "text file" with a name ending in .txt. ASCII text files can be created with text editors, such as TextEdit and Notepad. They are typically used for writing computer programs because executable program code cannot include formatting such as underlining and special fonts. They can also be used for creating Web pages. Text files can usually be opened by any word processing software regardless of the type of device. In that sense, they are universal. ASCII text files contain no formatting. They have no bold, italics, underlining, or font colors. There are no margins, columns, bullets, headers, or page numbers.

Binary Number System

The binary number system has only two digits: 0 and 1. No numeral like 2 exists in this system, so the number "two" is represented in binary as 10 (pronounced "one zero").

Digitization

The process of converting information, such as text, numbers, photos, or music, into digital data that can be manipulated by electronic devices is called digitization.

Data Compression

To reduce file size and transmission times, digital data can be compressed. Data compression refers to any technique that recodes the data in a file so that it contains fewer bits. Compression is commonly referred to as "zipping." Many compression techniques exist. They can be divided into two categories: lossless and lossy. Compressed files usually have .zip at the end of the file name and are represented with specialty icons. Compressed files may also end with .gz, .pkg, or .tar.gz. These files have to be extracted or unzipped before you can view the data they contain.

UTF-8

UTF-8 is a variable-length coding scheme that uses seven bits for common ASCII characters, but uses 16-bit Unicode as necessary.

Unicode

Unicode (pronounced "YOU ni code") uses sixteen bits and provides codes for 65,000 characters—a real bonus for representing the alphabets of multiple languages.