In backup strategies, what does a Differential Backup save?

A differential backup saves changes made since the last full backup. This means that every time a differential backup is executed, it captures all the data that has been altered, added, or deleted since the last full backup, rather than just the changes since the last backup session. This characteristic allows for a more streamlined recovery process, as the last full backup and the latest differential backup can be used together to restore data without needing to reference multiple backup sets.

For instance, if a full backup is done on a Sunday, and differential backups occur on Monday, Tuesday, and Wednesday, the Monday backup would include all changes since Sunday, the Tuesday backup would include all changes since Sunday, and the Wednesday backup would also include all changes since Sunday. In terms of recovery, you would only need the last full backup and the most recent differential backup to restore the data, making this method simpler and generally faster for recovery when compared to incremental backups, which depend on every prior backup made.