Present Perfect

Past Simple

Describes finished unfinished actions that started in the past and continue to the present.

I've been friends with Jack for ten years. We are still friends

Expresses finished unfinished actions.

I was Jack's friend for ten years. We lost touch

Refers to definite indefinite time.

I have seen the Colosseum

Refers to definite indefinite time.

I saw the Colosseum in 2012

Expresses an experience or a finished action with without a result in the present.

I've lost my purse. The result: I don't have my purse with me

A finished action with without a result in the present.

I lost my credit card yesterday. I made a new one. No result. The card wasn't found

With a finished an unfinished time period (this week, this month, today).

I've seen my mum today

With a finished an unfinished time period (last week, last month, yesterday).

I saw my mum last Saturday