Use of the Present Perfect
In British English the present perfect tense is used to express an action that has occurred in the recent past that has an effect on the present moment. For example:
I’ve (I have) lost my key. Can you help me look for it? In American English the following is also possible: I lost my key. Can you help me look for it?
Other differences involving the use of the present perfect in British English and simple past in American English include already, just and yet.