10⁹, one billion (1,000,000,000) bytes. SI symbol: GB
"The new smartphone comes with a gigabyte of free cloud storage space."
In plain English: A gigabyte is a huge amount of digital storage space that holds thousands of photos, songs, and videos on your phone or computer.
"My new phone has enough storage to hold over fifty gigabytes of photos and videos."
Usage: In technical contexts, "gigabyte" strictly denotes $10^9$ bytes according to the SI standard, though some computing systems historically used it to mean $2^{30}$ (approximately 1.07 billion) bytes. When precision is required, specify whether you are referring to decimal or binary units to avoid confusion with terms like gibibyte.
The word gigabyte combines the prefix giga- with byte to describe a unit of digital information equal to one billion bytes. It entered English as a straightforward technical term for large data storage capacity in the computing age.