The Big Difference
This is one of the most common mistakes in English. The rule is actually simple: Past Simple = you know (or mention) when it happened. Present Perfect = you don’t say when, or the time period isn’t over yet.
Past Simple
Finished time, specific moment known or mentioned.
I saw that film last week.
Present Perfect
No specific time / connection to now / unfinished time.
I ‘ve seen that film. (at some point)
Side-by-Side Comparison
I visited Paris in 2019.
Past Simple — specific year given
I ‘ve visited Paris.
Present Perfect — no time mentioned
She called me this morning. (morning is over)
Past Simple — finished time period
She ‘s called me today. (today is not over)
Present Perfect — unfinished time period
Did you ever meet him? (he’s dead)
Past Simple — person no longer alive
Have you ever met him? (he’s alive)
Present Perfect — still possible to meet
Past Simple signal words (specific, finished time):
yesterdaylast week/year
in 2015ago
when I was young
in 2015ago
when I was young
✗ Wrong
I have seen him yesterday.
yesterday = finished time → Past Simple
✓ Correct
I saw him yesterday.
Specific finished time → Past Simple
💡 Memory Hack
The “news bulletin” test
Imagine you’re a news presenter. Breaking news → Present Perfect: “A plane has landed safely.” Then reporters give details → Past Simple: “The plane landed at 3pm. The pilot made an emergency decision.” The headline uses PP; the story uses PS. Ask yourself: am I announcing it (PP) or telling the story (PS)?