A backup application is copying only changed files each time it runs.

This is the best description of a synthetic full backup method because it creates a full backup by combining previous incremental backups with the latest backup. An incremental backup copies only the files that have changed since the last backup, while a full backup copies all the files. A synthetic full backup reduces the storage space and network bandwidth required for backups, while also simplifying the restore process by using a single file.References:https://www.veritas.com/support/en_US/doc/129705091-129705095-0/br731_wxrt-tot_v131910378-129705095