Why do computers use binary?
Short answer
Computers use binary because electronic circuits can tell apart two signals reliably. A single 0 or 1 is called a bit. Parts called transistors control the flow of electricity, helping circuits create and combine these two states.
How it works
Many circuits treat a range of lower voltages as 0 and a range of higher voltages as 1. Each range allows some variation, so small changes in voltage are less likely to confuse the two values. If the same voltage range had to represent ten levels, those levels would be closer together and easier to confuse. So 0 and 1 do not simply mean “no electricity” and “electricity”; they label the circuit’s signal states.
Bits can be combined to represent more information. Three bits, for example, can form eight patterns, from 000 to 111. Rules tell the computer which patterns stand for numbers and characters.