What is a gigabyte?

A byte is usually 8 bits, and a bit is a single 0 or 1. In the decimal system used by storage makers, a gigabyte (GB) is 1,000,000,000 bytes, while operating systems sometimes count in powers of two, where 1 gibibyte is 1,073,741,824 bytes. That is why a new drive often shows less space than advertised. A gigabyte can hold roughly 250 average songs in MP3 format or around an hour of standard-definition video, depending on quality. Beyond it come terabytes (1,000 GB), petabytes and exabytes.