Eight bits. A bit (Binary digIT) is a single unit of data having two possible states: 1 or 0. A byte is a collection of eight bits to produce 2^8 possible states (256) and faster communication. Examples of larger collections of bytes are kilobytes (kB - notionally 1,000 bytes (8,000 bits)), megabytes (MB, one million) and gigabytes (GB, one billion). Note that bytes are represented by a capital B, while bits are represented by a lower-case b. It is convention for amounts of data to be referred to in bytes e.g. 2MB; while data transfer speeds shown in bits e.g. 16Mb (or 16Mbps (per second)).