We use the past simple to refer to definite time in the past (when we specify the time or how long) and usually with past time expressions such as yesterday, two weeks ago, last year, in 1995:
We use the present perfect to talk about time up to now, that is, events that took place in the past but which connect with the present. The present perfect is often used with time expressions which indicate time up to now, for example today, this year, in the last six months:
