The full form of GB is GigaByte. It is a unit of digital storage capacity that is roughly equivalent to 1 billion bytes. In the International System of Units (SI), the prefix "giga" means 10^9, so one gigabyte is equal to one billion bytes. A gigabyte has been a common unit of capacity measurement for data storage products since the mid-1980s. It is used to describe the amount of stored data or the capacity of a storage device. The term GB is commonly used to refer to digital data, and it is the fourth-largest unit of telecommunication-related data.