The binary number system is a base-2 number system. This means it only has two numbers: 0 and 1. All information in a computer (words, pictures, movies, sound) is stored and transmitted as sequences of bits, or binary digits.

A bit is a single piece of data which can be thought of as either zero or one. Each binary number is made up of bits, for example, the number 1010 is made of 4 bits. When you have 8 bits altogether, this is known as a byte. A byte may look like the number 01000100 and in this case represents the letter 'D'.

A use of two states or permissible values to represent *data*, such as ON and OFF positions of a light switch or transistors in a computer silicon chip that can be in either the electrical state of ON or OFF.

*Binary* data are typically represented as a series of single digits referred to as binary digits (or bits) due to each taking on the value of either 0 or 1. The image below shows how a dashed line might be represented in binary.

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Recognise and explore patterns in data and represent data as pictures, symbols and diagrams (ACTDIK002)

Recognise different types of data and explore how the same data can be represented in different ways (ACTDIK008)

Examine how whole numbers are used to represent all data in digital systems (ACTDIK015)

Investigate how digital systems represent text, image and audio data in binary (ACTDIK024)

Analyse simple compression of data and how content data are separated from presentation (ACTDIK035)