The gigabyte (/ˈɡɪɡəbaɪt/ gig-ə-byt or /ˈdʒɪɡəbaɪt/[1]) is a multiple of the unit byte for digital information.
The prefix giga means 109 in the International System of Units (SI), therefore one gigabyte is 1000000000bytes. The unit symbol for the gigabyte is GB.
This definition is used in all contexts of science, engineering, business, and many areas of computing. However, historically, the term is also used in some fields of computer science and information technology to denote1073741824 (10243 or 230) bytes.
The term "gigabyte" is thus ambiguous today. For semiconductor RAM, the "gigabyte" denotes1073741824bytes. For hard drive capacities as described and marketed by the drive manufacturers, the gigabyte denotes 1000000000bytes, but when a "500 GB" drive's capacity is displayed by, for example, Microsoft Windows, it will be reported as 466 GB (where "GB" means 1073741824bytes).
To address this ambiguity, several standards organizations have defined a set of "binary prefixes", unique prefixes denoting powers of 1024. According to these, "gigabyte" or "GB" would always refer to 1000000000bytes, and what is now labeled as a "1 GB" RAM module would be described as "1 GiB" or "one gibibyte". However, these have seen only limited usage in product labeling and software.
