A gibibyte is a unit of data storage that equals 2 to the 30th power, or 1,073,741,824 bytes.
While a gigabyte can be estimated as 10^9 or 1,000,000,000 bytes, a gibibyte is defined as exactly 1,073,741,824 bytes. This helps avoid the ambiguity associated with the size of gigabytes. A gibibyte is 1,024 mebibytes and precedes the tebibyte unit of measurement.
For a list of other units of measurement, view this Help Center article.