Russian verbs of motion

What is the difference between войти and зайти?

The following prefixes make sense to me... вы means out в means in от means away при means to come or arrive What does the prefix "с" mean with verbs of motion? I've read...

Why do we say "Автобус ходит по этому маршруту" and not "ездит"?

What is the difference between пойти and прийти?

Hi! From what I read I figured out that unidirectional verbs are imperfective verbs and that multidirectional verbs are perfective verbs. But I'm not sure. Is that so? Thank you....