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?
Yes, it means afterward or afterwards. It can also mean subsequently, later, hereafter, at a later time, or later today of course depending on the context. And bis nachher means "till then or until then". Hope this helps.
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".
nach + noun, f.i. "Wir gehen nach dem Essen!"
nachdem + sentence, f.i. "Wir gehen, nachdem wir gegessen haben!"
nachher is used when everybody knows what the "after" refers to, f.i. "Wir gehen nachher!"