Understanding REDO changes applies to datafiles

Hi Team,

I'm facing some problem understanding the concept of "how the REDO log changes are applied to the datafiles"

Whenever a transaction is commited the Change vector (ie update,inserted DML statement data)goes to the Online redo logs from the REDO log buffers.

However, how does database will come to know that what changes within the REDO logfiles will be applied to which datafiles (more specifically which data block).

My assumption is that it'll check the last SCN of the REDO, and then will make all the datafiles consistent upto that SCN no.

However I just wanted to havea clear picture regarding this topic.