The prefix "giga" denotes a factor of one billion, or 10^9. It is commonly used in various fields, including computing and science, to describe large quantities. For example, a gigabyte (GB) represents approximately one billion bytes of data storage. In the International System of Units (SI), "giga" is part of a series of prefixes that indicate multiples of ten. Other prefixes include mega for one million and tera for one trillion. The use of "giga" helps simplify communication about large numbers, making it easier to understand and compare measurements.