​The present perfect is formed from the present tense of the verb have and the past participle of a verb.

We use the present perfect:

• for something that started in the past and continues in the present:

• ​She has lived in Liverpool all her life.

when we are talking about ourexperience up to the present:

• I've seen that film before.

​We often use the adverb ever to talk about experience up to the present:

​My last birthday was the worst day I have ever had.

​and we use never for the negative form:

• Have you ever met George?

• Yes, but I've never met his wife.