The gigabyte (/ˈɡɪɡəbaɪt/ GIG-ə-byt or /ˈdʒɪɡəbaɪt/) is a multiple of the unit byte for digital information. The prefix giga means 10 9 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, including hard drive, solid state drive, and tape capacities, as well as data transmission speeds.he term gigabyte is commonly used to mean either 1000 3 bytes or 1024 3 bytes. The latter originated as compromise technical jargon for byte multiples that needed to be expressed by the powers of 2 but lacked a convenient name.