The perfect aspect

have + past participle

The perfect aspect is expressed with the auxiliary have and the past participle form of the verb. Depending on the time of the action, we use one of the following forms of have: the past (had), present (have, has), modal + infinitive (e.g. will have) or -ing (having).

The perfect aspect focuses on the completion of an event. It expresses that the action had, has or will have been completed by a specific point in time. This point in time may be defined by a time expression (by 5 o'clock) or a clause (by the time you get home, when I arrived).

Examples of the perfect aspect:

I've lived here for ten years. (from 10 years ago until now)
By 5 o'clock, he had finished the letter. (at some time before 5 o'clock)
When I arrived, they had already left. (at some time before I arrived)
Have you seen my new bike? (at any time up to now)
I will have done the ironing by the time you get home. (between now and when you get home)
He might have missed the train. (at some time before now)
Having taken the wrong turn, he ended up in a dangerous neighbourhood. (he took the wrong turn before he found himself in a dangerous neighbourhood)