giga- (symbol: G) is a prefix in the SI system of units denoting 109, or 1 000 000 000.
Confirmed in 1960, it comes from the Greek γίγας, meaning giant.
In computing, giga- can sometimes mean 1 073 741 824 (230) for information units, eg gigabit or gigabyte, but can also denote 1 000 000 000 of other quantities, e.g. transfer rates: 1 gigabit/s = 1 000 000 000 bit/s. The binary prefix gibi- has been suggested for 230, to resolve this ambiguity, but has yet to achieve widespread usage.
Pronunciation
In English the initial G of giga can be pronounced with a soft G as in jig, or with a hard G as in giggle. The latter hard G pronunciation has become more common, especially when referring to computer measurements such as gigabyte and gigahertz. An example of the soft G pronunciation is found in the 1985 movie Back to the Future, where gigawatts was pronounced as jigawatts. This was before units like gigabyte became common, and was used to emphasize magnitude, since quantities that large were rare at the time. One conjecture for the ascendant popularity, in the United States, of the hard G pronunciation is that it is a reaction to the way the soft G pronunciation places the word gigabyte so phonetically close to the racial slur "jigaboo".
Common usage
- Gigabyte — hard disk capacity, e.g. 120 GB; DVD capacity, e.g. 5 GB = 5 × 1 073 741 824 bytes
- Gigahertz — clock rate of a CPU, e.g. 3 GHz = 3 000 000 000 Hz
- Gigabit — bandwidth of a network, e.g. 1 Gbit = 1 000 000 000 bit/s
- Gigabort - Common slang expression that could represent any of the above. Used to mock those that don't know the difference between bytes, bits, hertz, etc.
See also
