| To talk about events in a Period of Time that is Not Finished: |
| Today I have learned a lot. I have visited London. (in my life) This year we have made a lot of progress. |
With certain words: already, yet, for, since, just |
| I have already paid. Have you finished yet? - No, not yet. I have lived here for 10 years. I have lived here since 1982. I have just learned something useful! |
I have visited
For comparative examples...
This year
For a diagram (Time Line) of this situation...
already
Speakers of American English often say:
"I already learned"...