Rather and Quite are adverbs we use to modify adjectives (and, occasionally, verbs and nouns). Quite falls between “more than a little” and “less than a lot.” Quite goes before a/an.

Examples:

She is quite friendly once you get to know her.
It’s quite a good movie, isn’t it?
He quite enjoys playing chess.

Rather has the same meaning as quite, but we generally use it with negative feelings or words. Rather can go before or after a/an.

Examples:

She is rather difficult to work with.
I don’t want to walk in the park; the weather is rather nasty.
He said a rather rude thing to me.

Quite is also used to mean “absolutely.”

Example:

I’m quite certain that this is the correct road.

Rather, when used with positive feelings or words, indicates surprise or that something is unexpected.

Example:

I normally don’t like opera, but that production of Aida was rather good.

Not quite means “not completely.”

Example:

I’m not quite sure what you mean.