The Present Perfect is used to indicate a link between the present and the past. The time of the action is before now but not specified, and we are often more interested in the result than in the action itself.

FORMING THE PRESENT PERFECT The Present Perfect of any verb is composed of two elements: have / has plus the past participle of the main verb. The past participle of a regular verb is base+ed, e.g. played, arrived, looked. For irregular verbs, see the table of irregular verbs.

THE PRESENT PERFECT IS USED TO DESCRIBE

An action or situation that started in the past and continues in the present. I have lived in Bristol since 1984 (= and I still do.)

An action performed during a period that has not yet finished. She has been to the cinema twice this week (= and the week isn't over yet.)

An action that was completed in the very recent past. I have just finished my work.

An action when the time is not important. He has read 'War and Peace'. (= the result of his reading is important)

Note: When we want to give or ask details about when, we use the Past Simple.