Bit

Off. On. 0 or 1. One bit.

Byte

Line them up. 8 bits make 1 byte.

Number

Each place counts double. A byte counts from 0 to 255. 01000001 is 65.

ASCII

Agree that 65 means A. ASCII, 1963: one table of 128 symbols. Look up each letter of HELLO, WORLD and spell anything.

Letter

Bytes on punched tape spell HELLO, WORLD. Text is numbers.

Color

Three bytes: red, green, blue. 16,777,216 colors.

Picture

One color is one pixel. More pixels. A grid of colors is a picture.

Sound

Sound is wiggling air. Measure it and write the number, 44,100 times a second.

Movie

One picture, then the next. 24 a second is a movie.

Game

Pictures plus rules plus you is a game.

Transistor

How does it decide? A transistor is a switch: a 1 on its input lets current flow. One transistor that steals the current from a lamp is NOT. Two in a row is AND. Two side by side is OR.

Logic

How does it decide? Logic gates. NOT flips a bit. AND outputs 1 only when both inputs are 1. OR outputs 1 when either is 1.

Chip

Wire an XOR gate and an AND gate together and they add: 1 + 1 = 10. Copy that circuit again and again: billions of switches flipping billions of times a second. That is how a computer thinks.

Everything

Then everything: messages, maps, music, money, medicine. All of it is 0 and 1.