Organisation of Data

Fundamental Units of Data

Bit: Short for ‘binary digit’, the smallest unit of data in a computer, representing a 0 or 1.
Nibble: A data unit containing 4 bits.
Byte: A data unit made up of 8 bits. The standard basic unit of data storage.

KB (Kilobyte): Approximately 1 thousand bytes. Precisely, 1 KB is 2^10 (or 1,024) bytes.
MB (Megabyte): Approximately 1 million bytes. Precisely, 1 MB is 2^20 (or 1,048,576) bytes.
GB (Gigabyte): Approximately 1 billion bytes. Precisely, 1 GB is 2^30 (or 1,073,741,824) bytes.

Boolean Data: Named after George Boole, it’s a data type with only two values: True or False. Used in logical operations.
Numeric Data: This can either be integers (whole numbers) or floating point numbers (numbers with a decimal point).
Character Data: Represents a single character such as a letter, number or symbol.
String Data: A sequence of characters. It can include letters, numbers and symbols.
Array Data: An organised set of data elements (such as numbers or characters) typically of the same data type.

Flat-file database: A database with just one table of data. No relationships exist between different sets of data.
Relational Database: A database with multiple tables of data that are connected in some way. Uses keys to link tables together.
Primary Key: A unique identifier for a record in a table. No two records can have the same primary key.
Foreign Key: A field in one table that uniquely identifies a row of another table. Used to link records in different tables.

Sorting: Arranging data in a particular sequence - often numerical or alphabetic.
Filtering: Choosing data from a dataset to display based on specific criteria.
Searching: Looking for specific data within a dataset. A ‘linear search’ looks through each item one by one, while a ‘binary search’ continually halves the dataset until the required data is found.

Data Protection Act: UK law that governs the protection and use of data in electronic form.
Encryption: The process of converting information or data into a code to prevent unauthorised access.
Backup: A copy of a file or other item of data, made in case the original is lost or damaged.