A) We use rather as an adverb of degree:

Modifying an adjective:

• The film was rather good.

Modifying an adverb:

• It happened rather quickly.

Notes:

1. It is stronger than fairly, but not as strong as very.
2. It can modify a noun, often coming before the article:
3. It's rather a problem.
4. It can modify some verbs: I rather like it.

B) To express preference

Rather than:

Rather than is normally used to compare parallel structures:

• Let's take the train rather than the bus.
• Rather you than me!
• I decided to write rather than email.

Would rather:

Would rather + infinitive without 'to':

• I'd rather leave now.

Would rather + pronoun + past tense:

• I'd rather he came early.