We use both, neither, and either to talk about two things.
Both = two things or two people together.
Both restaurants are expensive. (restaurant 1 and restaurant 2)
Neither = not one and not the other.
Neither restaurant is cheap. (restaurant 1 is not cheap and restaurant 2 is not cheap)
Either = one or the other (we don't say which one).
We can go to either restaurant. (it doesn’t matter which)
You can also use:
Both ... and - Both Chris and Pat are late.
Neither ... nor - Neither Chris nor Pat came.
Either ... or - Either you call me, or I’ll call you.