The quick answer

Use the past simple for a finished action at a definite past time — often with words like yesterday, last week, in 2019, ago. Use the present perfect when the past connects to now: an experience with no stated time, a very recent action, or a past action with a result you can still see.

The rule

The past simple closes the door on the past: the time is finished and stated or understood — I visited Paris in 2019. The present perfect keeps the door open to now — I have visited Paris (some time in my life, up to now). If the sentence gives a finished past time, you must use the past simple; if it talks about your experience up to now, or uses just, already, yet, ever, never, so far, this week (period not finished), use the present perfect.

Form

Examples

• I saw Anna yesterday. (finished time: yesterday)
• I have seen that film three times. (experience, up to now)
• She has just finished her homework. (very recent, result now)
• We went to Rome in 2018. (definite past time)
• Have you ever eaten sushi? (experience in your life)
• He hasn't called me this week. (period still open)

Common mistakes

• ❌ I have seen her yesterday. → ✅ I saw her yesterday. A finished time word (yesterday) needs the past simple.
• ❌ Did you ever be to London? → ✅ Have you ever been to London? Life experience with 'ever' takes the present perfect.
• ❌ I have finished my work two hours ago. → ✅ I finished my work two hours ago. 'ago' marks a finished past time, so use the past simple.
• ❌ She has went home. → ✅ She has gone home. The present perfect uses the past participle (gone), not the past simple (went).