Nach, nachdem, nachher
I'm not sure of the usage of these three words. As I understand it, "nach " means "after", "nachdem" means "after that", and I'm not clear on "nachher" but perhaps means afterwards. Any comments out there?
nachdem is also a conjunction, "after".
For example, nach dem Regen "after the rain" but nachdem es geregnet hatte "after it had rained".
The difference is that the preposition nach stands before a noun or noun phrase but the conjunction nachdem stands before an entire clause (with a verb in it).
You can't say nach es geregnet hatte for "after it had rained".