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.