Quaisar,

You should definately read the documentation regarding this subject. It is SO large and detailed. There would be no point to describe EVERYTHING that these two things do. Also, Do a "search" on this Forum for archives regarding this information.

Basically, archived logs and redo logs are a KEY ingredient to any Backup&Recovery procedure. In fact, it would be fairly impossible to Recover a database if you did not have any of these logs (backed up or otherwise).

You cannot run a database without redo logs.

Again, read the archives on this subject or Oracle Documentation. There is way too much information out there to go into detail on this broad subject.

- Magnus