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What is binary code?

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Quick answer

Binary is a number system that uses only two digits, 0 and 1. Computers use it because their circuits have two states — on and off — so every piece of data is ultimately stored as binary. Each digit is a 'bit'; eight bits make a 'byte'.

Key things to understand

  1. Each digit is a 'bit'; eight bits make a 'byte'.
  2. Place values double (1, 2, 4, 8, 16…) instead of the tens of the decimal system.
  3. All data — text, images, sound — is encoded as binary numbers.
  4. On/off transistors map naturally to 1 and 0.

People also ask

Why do computers use binary?
Because electronic circuits reliably represent two states (on/off), which map cleanly to 1 and 0.
How do you count in binary?
Place values double: 1 is 1, 10 is 2, 11 is 3, 100 is 4, and so on.
What is a bit and a byte?
A bit is a single 0 or 1; a byte is eight bits and can represent 256 different values.