How DNA proofreading and repairing occur?

Question

I saw some stuff on SparkNotes, but I still don't get it.

Answer 1

When pol III prepares to add a new base to the new DNA molecule it needs to be precisely aligned. If the last base that was added was wrong it will not form a stable base pair, and this means the polymerase is mis-aligned. In this case the pol III uses its exonuclease ability to remove the previous base, backs up, and tries again. It does not need either pol I or ligase to perform these steps, they are all intrinsic functions of pol III itself.

Answer 2

After the process has been completed the DNA molecules undergo proof reading. DNA polymerase is the enzyme that checks for these errors. If a repair is needed DNA polymerase and ligase will identify, cut, remove, and correct the mistake. This is called Excision repair.