Giga-

Template:Short description Template:Other uses

Laptop hard drive, with its platter exposed.

Giga- (Template:IPAc-en or Template:IPAc-en) is a unit prefix in the metric system denoting a factor of a short-scale billion or long-scale milliard (10⁹ or 1,000,000,000). It has the symbol G.

Giga- is derived from the Greek word Template:Lang (gígas), meaning "giant". The Oxford English Dictionary reports the earliest written use of giga in this sense to be in the Reports of the IUPAC 14th Conférence Internationale de Chimie in 1947: "The following prefixes to abbreviations for the names of units should be used: G giga 10⁹×."<ref>Template:Cite web</ref> However, it was already used in 1932 by the German organization Verband deutscher Elektrotechniker.<ref>Template:Cite web</ref>

When referring to information units in computing, such as gigabyte, giga may sometimes mean Template:Gaps (2³⁰); this causes ambiguity. Standards organizations discourage this and use giga- to refer to 10⁹ in this context too.<ref name="BIPM">Template:Cite book</ref><ref name="NIST">NIST Guide for the Use of the International System of Units (Appendix D. ref 5)</ref>Template:Primary source inline Gigabit is only rarely used with the binary interpretation of the prefix. The binary prefix gibi has been adopted for 2³⁰, while reserving giga exclusively for the metric definition.

Pronunciation

In English, the prefix giga can be pronounced Template:IPAc-en (a hard g as in giggle), or Template:IPAc-en (a soft g as in gigantic, which shares gigaTemplate:'s Ancient Greek root).<ref>Template:Cite web</ref> A prominent example of this latter pronunciation is found in the pronunciation of gigawatts in the 1985 film Back to the Future.

According to the American writer Kevin Self, a German committee member of the International Electrotechnical Commission proposed giga as a prefix for 10⁹ in the 1920s, drawing on a verse (evidently "Anto-logie") by the German humorous poet Christian Morgenstern that appeared in the third (1908) edition of his Template:Lang (Gallows Songs).<ref>Template:Cite book [These lines are the only appearance of gig in the book. Template:Lang is German for "giant"; cf. "gigantic".]</ref><ref>Template:Cite book</ref> This suggests that a hard German Template:IPA was originally intended as the pronunciation. Self was unable to ascertain when the Template:IPA (soft g) pronunciation came into occasional use, but claimed that as of 1995 it had returned to Template:IPA (hard g).<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>

In 1998, a poll by the phonetician John C. Wells found that 84% of Britons preferred the pronunciation of gigabyte starting with Template:IPA (as in gig), 9% with Template:IPA (as in jig), 6% with Template:IPA (guy), and 1% with Template:IPA (as in giant).<ref>Wells, J. C. (1998). LPD pronunciation preference poll 1998.</ref>

Common usage

gigahertz—clock rate of a CPU, for instance, 3 GHz = Template:Gaps
gigabit—bandwidth of a network link, for instance, 1 Gbit/s = Template:Gaps.
gigabyte—for instance, for hard disk capacity, 120 GB = Template:Gaps;
gigayear or gigaannum—one billion (10⁹) years, sometimes abbreviated Gyr, but the preferred usage is Ga or, for years ago, GA.<ref>Template:Cite journal</ref>

Template:SI prefixes (infobox)

Binary prefix

The notation Template:Val represents 1,000,000,000 bytes or, in deprecated usage, 1,073,741,824 (2³⁰) bytes. Per IEC 60027-2 A.2 and ISO/IEC 80000 standards, the correct notation of 2³⁰ is gibi (symbol Gi).<ref>Template:Cite web</ref> One gibibyte (Template:Val) is 1,073,741,824 bytes or Template:Val. Despite international standards, the use of Template:Val = 2³⁰ B is widespread. A laptop advertised as having Template:Val has 8,589,934,592 bytes of memory: Template:Val, or Template:Val. <ref>Template:Cite web</ref>