Present perfect for recent events with a result in the present

The present perfect tense is used for recent events that have a result in or an effect on the present moment:

Someone has opened the window. (the window is open, and it is cold inside)
Tom has broken his leg. (his leg is broken, and he can't walk)

If there is no connection between the action and the present moment, the past simple is used:

Someone opened the window to let in some fresh air. (the window is now closed, or we don't know whether it is closed or not)
On the day before the match, Tom broke his leg. (his leg is not broken anymore)