Light switches all the way down
A row of light switches, each on or off, can spell out any number if you agree what each position means. Computers store everything — numbers, text, photos — as rows of these on/off switches: binary, just 1s and 0s.
Two symbols, any number
Computers store everything as bits — 1s and 0s. Just like our decimal system uses powers of ten, binary uses powers of two. Each place to the left is worth twice the one before: 1, 2, 4, 8, 16, …
00001010 = 8 + 2 = 10
Simulation · Binary counter
1286432168421
binary 00001010 = 10
Toggle the bits on and off and watch the decimal value. Each bit you switch on adds its place value.