We use the Simple Past Tense to talk about actions in the past that have finished. It talks about ‘then’ and definitely excludes ‘now’.
We use the Present Perfect Tense to look back on actions in the past from the present. It always includes ‘now’.
I first met him 10 years ago.
I started work here in 1987.
I ate too much at lunchtime.
I’ve known him for 10 years.
I’ve worked here since 1987.
Typical time phrases that we use with the past simple are ‘yesterday’, ‘ago’, ‘last year’, ‘in 1999’.
She came in a few moments ago.
We made our last purchase over a year ago.
He joined the company in 1999.
Typical time phrases that we use with the present perfect are ‘ever’, ‘never’, ‘since’.
I’ve never seen so many people.
Have you ever been more shocked?
I’ve done a lot since we last spoke.
Typical time phrases always used with the present perfect in British English but often used with the past simple in American English are ‘already’, ‘just’, ‘yet’.
The time phrase ‘for’ can be used with both forms, but with different meanings.
I went to Munich for the weekend but I came back on Sunday evening.