Meaning of “I'd” - Learner’s Dictionary

I'd

us uk /aɪd/
I'd already eaten.I'd seen it before.I'd told her I wasn't coming.I'd hate to upset her.I'd love to come
I HAD

short for I had:

Everyone thought I'd gone.
I WOULD

short for I would:

I'd like to buy some stamps, please.

(Definition of “I'd” from the Cambridge Learner’s Dictionary © Cambridge University Press)