Binary: how computers represent information — Computing, 11–13 years
Computers represent information with patterns of two states, written as 0 and 1. Computing, 11–13 years.
What binary means
Binary is a way of writing numbers and other information using only two symbols: 0 and 1. A computer’s tiny switches can be in one of two states, so these symbols fit its hardware. Groups of bits can represent numbers, letters, colours or sounds.
Why computers use binary
Electronic parts can reliably tell two states apart: for example, a signal present or absent. Using two states is less prone to confusion from small electrical changes than trying to distinguish many levels. Binary is therefore a practical language for storing and processing information inside machines.
Worked example: binary 1011
Read 1011 from right to left. Its place values are 1, 2, 4 and 8; multiply each by its bit: 1×1, 0×2, 1×4 and 1×8. Add the results, 1+0+4+8, to get 13 in our usual decimal notation.
Trap: treating binary like decimal
A common mistake is reading 1011 as one thousand and eleven, or adding its digits as if they were decimal. That is reasonable because decimal is the notation we use every day. In binary, each place is worth twice the place to its right, so the places here are 8, 4, 2 and 1.
Where binary appears
Photos, messages, games and music are all stored as patterns of bits inside devices. A colour may be represented by numbers for its red, green and blue parts, while sound is stored as measured samples. Screens and speakers turn those stored patterns back into things we can see and hear.
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