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.
Actions started in the past and continuing in the present
They haven't lived here for years.
She has worked in the bank for five years.
We have had the same car for ten years.
Have you played the piano since you were a child?
When the time period referred to has not finished
I have worked hard this week.
It has rained a lot this year.
We haven't seen her today.
