Usage Note: The usual meaning of the prefix giga- is one billion, so one would expect the term gigabyte to refer to one billion bytes. However, in describing the capacity of an electronic device that stores digital data, it often has a special meaning, referring to the power of 2 closest to one billion, which is 2³⁰, or 1,073,741,824 bytes. This special meaning comes about because storage devices use binary numbers to keep track of storage locations, and so are often designed with a number of storage locations that is a power of 2. Nonetheless, for reasons of convenience manufacturers of hard drives generally use gigabyte when they mean a rounded off sum of 1 billion bytes. In other aspects of technology, such as data transmission, where powers of 2 are less relevant, a gigabyte normally means exactly 1 billion bytes. Other prefixes, such as mega- and tera-, show a similar pattern in use.