This graphic shows backups made at levels 0, 1, 2, 3, 2, and 3. The level 1 backs up data changed since the 0; the level 2 backs up data changed since the 1; the level 3 backs up data changed since the 2; the level 2 backs up data changed since the 1; the level 3 backs up data changed since the most recent 2.