Oracle Background Processes

People often ask in DBA interview what are the oracle background process and describe then

There are many type of oracle background processes each performing specified job but oracle
require five background process
1. System Monitor (SMON)
Perform instance recovery when instance crash, this process also manage space that is used during sorting
2. Process Monitor (PMON)
Process monitor cleans up failed user database connections.
3. Database Writer (DBwn*)
Write modified database blocks from SGA buffer cache to datafiles on disk(n means it can be more then one 20 max)
4. Log Writer (LGWR)
Write transactions recovery information from Redo log Buffer to online Redo Log Files
5. Checkpoint (CKPT)
Updates the database files following a checkpoint event