In incremental backup it copies only the files that have changed since the last full backup. It does not backup all the files just like the full backup. it however backup those copies into the system which has changed since the last backup.
In doing so it just increases the efficiency and performance of the backup procedure. This process is basically preferred when the amount of file to be backup is huge and there is not enough time to do a full backup.
Increment backup also use less disk space.
Cloud backup uses most increment backup for its application.
