Gigabit

A gigabit (symbol Gb) is a unit of measure for data transfer or storage equal to one billion bits.

Because of the relationship of bits to bytes (8 bits = 1 byte), it is a significant difference in overall storage quantity should the two nomenclatures be confused. Typically, bytes are used for physical storage (eg. 20GB capacity), while bits are used for throughput or bandwidth ratings (eg. 400 Mb/s transfer rate).