In computer architecture, a word is a unit of data of a defined bit length that can be addressed and moved between storage and the computer processor. Usually, the defined bit length of a word is equivalent to the width of the computer's data bus so that a word can be moved in a single operation from storage to a processor register. For any computer architecture with an eight-bit byte, the word will be some multiple of eight bits. In IBM's evolutionary System/360 architecture, a word is 32 bits, or four contiguous eight-bit bytes. In Intel's PC processor architecture, a word is 16 bits, or two contiguous eight-bit bytes.
Some computer processor architectures support a half word, which is half the bit length of a word, and a double word (doubleword), which is two contiguous words. Intel's processor architecture also supports a quadword, two contiguous doublewords, and a double quadword, two contiguous quadwords.
A word can contain a computer instruction, a storage address, or application data that is to be manipulated (for example, added to the data in another word space). In some architectures, a double word or larger unit is required to contain an instruction, address, or application data. Typically, an instruction is a word in length, but some architectures support halfword and doubleword-length instructions.
In general, the longer the architected word length, the more the computer processor can do in a single operation.