A bit is the smallest unit of digital information. It has two possible values: 0 or 1. Everything digital is built from bits. Text, images, video, and sound are all encoded as sequences of zeros and ones. Eight bits make a byte. A thousand bytes make a kilobyte. A million make a megabyte.

The term was coined by Claude Shannon in 1948. He was working at Bell Labs on information theory. He showed that any message could be encoded as bits. The bit is the atom of the information age. It is abstract but concrete. It is a distinction between two states: on or off, high or low, yes or no.

Common bit units

• Bit: 0 or 1
• Byte: 8 bits
• Kilobit: 1,000 bits
• Megabit: 1,000,000 bits
• Gigabit: 1,000,000,000 bits

Network speeds are measured in bits per second. File sizes are measured in bytes. That is why a 100 Mbps connection downloads a 100 MB file in about 8 seconds, not 1. The bit is small. But billions of them move every second through the networks that connect the world.