Binary is a numbering system that uses only two digits: 0 and 1. It is the fundamental language of virtually all computers and digital devices.

While we count in the decimal system (with 10 digits, from 0 to 9), computers use the binary system because it is perfect for representing the two states of an electronic circuit: on or off.

• On = 1

• Off = 0

All digital information — audio, images, text, etc. — is, at its most fundamental level, a long sequence of zeros and ones. Each 0 or 1 is called a bit. These states can be physically represented in several ways:

• A high (1) or low (0) voltage in a circuit.

• A pulse of light (1) or the absence of light (0) in a fiber optic cable.

• A magnetized area in one direction (1) or the other (0) on a hard drive.