Conditional perfect is an English grammatical tense. It relates an action that someone would have done.
Form: would + have + past participle ( past participle -> (infinitive + -ed) or (3rd column of the table of the irregular verbs) )
We use it for something that might have happened in the past.
We use it in the main clause in type III of the if clauses.
You would have gotten more money if you had worked harder.
If we had run faster, we would have arrived earlier.
If I were a woman, I would have entered the contest.
Would you have traveled around the world?
I wouldn't have stayed in my hometown.
It is also possible for the auxiliary would to be replaced by the modals should, could or might to express appropriate modality in addition to conditionality.
Sometimes, in informal speech, the would have construction appears in the if-clause as well ("If we would have run faster, we would have arrived earlier"), but this is considered incorrect in formal speech and writing.