Data Types and How Computers Represent Data

What is Data?

Data refers to raw, unorganised facts and figures that have not yet been processed into meaningful information. Once data is processed (organised, analysed, and interpreted), it becomes information that people can use to make decisions.

Types of Data

• Numeric data: data consisting of numbers, e.g. 25, 3.14, 1000. Used for calculations.
• Alphabetic data: data consisting only of letters, e.g. names like "John".
• Alphanumeric data: data consisting of a mixture of letters, numbers and symbols, e.g. "Room12A" or an email address.
• Boolean data: data with only two possible values — true or false (yes or no).
• Image, audio and video data: multimedia data representing pictures, sound, and moving images.

How Computers Represent Data

Computers do not understand data the way humans do; internally, all data — whether numbers, text, images or sound — is converted into binary code (a series of 0s and 1s), since computer circuits only recognise two electrical states: on (1) and off (0).

Units of Data Storage

• Bit: the smallest unit of data, a single 0 or 1.
• Byte: a group of 8 bits, enough to represent one character (like a letter or digit).
• Kilobyte (KB): approximately 1,024 bytes.
• Megabyte (MB): approximately 1,024 kilobytes.
• Gigabyte (GB): approximately 1,024 megabytes.

Character Encoding

To represent letters and symbols in binary, computers use character encoding systems such as ASCII (American Standard Code for Information Interchange), which assigns a unique binary code to each character. For example, the uppercase letter "A" is represented as 65 in ASCII, which is 01000001 in binary.

Why Data Representation Matters

Understanding how computers represent and store data helps explain how files take up storage space, why some files are larger than others (like videos versus text documents), and how computers can process such a wide variety of information using just two digits: 0 and 1.