We can use subject + would + infinitive (I would go) or subject + would + have + past participle (I would have gone).
'Would' has quite a lot of different uses. It's often a kind of past tense version of 'will'.
Remember that both 'had' and 'would' can be shorted to 'd. But only 'would' is followed by an infinitive without 'to'. 'Had' is followed by a past participle or by 'to + infinitive'.
1: The past of 'will' in reported speech
When we use 'will' in direct speech, we often use 'would' to change it into reported speech.
- Direct speech: I will be there at 6pm.
- Reported speech: She said that she would be there at 6pm.
- Direct speech: We won't see you at the party.
- Reported speech: They said that they wouldn't see us at the party.
2: Willingness in the past
In the present we use 'will' to talk about willingness (willingness means that you are happy to do something). For example, if we say 'I will help you', this means 'I'm offering to help you' or 'I'm happy to help you'. We use 'would' for the same meaning in the past. Usually, we use this in the negative (when we are not happy to do something) and we use 'won't' for the present and 'wouldn't for the past'.
- His mother won't let him go to the party.
- His mother wouldn't let him go to the party.
- When we were children, we would go to the beach every summer.
- When I lived in Japan, I would take Japanese lessons three times a week.
(We can also use 'will' for typical behaviour or habits in the present, though this is much less common than using 'would' for the past. An example in the present is 'she'll talk and talk for hours!')
4: Requests
We use both 'will' and 'would' to make requests. The meaning is the same for both, but a request with 'would' is more polite than a request with 'will'.
- Will you please help me?
- Would you please help me?
We use 'would + infinitive' in the second conditional.
- If I had enough money, I would travel around the world.
- If we lived in Madrid, we would study Spanish.
6: The third conditional
We use 'would + have + past participle' in the third conditional.
- If I had gone to bed earlier, I wouldn't have been so tired.
- If the train hadn't been late, we would have arrived on time.
Read about 'could have' / 'would have' / 'should have' here.
7: With 'wish'
- I wish that he wouldn't smoke so much.
- I wish you would come to see me more often.
8: With set phrases to talk about what we want
We use 'would' with some set phrases. These have some 'willingness' meaning in them.
- I would like some coffee.
- She would rather go to the cinema.
- We would prefer to leave immediately.
- Would you mind helping me?