Term: incremental backup

An incremental backup is a backup of only those files changed since them immediately preceding backup. The term derives from the word “increment,” in that only an increment of the entire collection of files will be included.

Incremental backups are used in conjunction with full backups as space-saving alternatives to backing up everything every time.

An incremental backup is used when backups are taken periodically. The first is a full backup of everything. Each subsequent backup in the series is incremental, backing up only those files which have been modified since the immediately preceding backup.

While incremental backups save space, they have a built-in dependency: to recover an entire collection of files to its most recent state, the initial full backup, plus all intervening incremental backups, must be available.