When used with present perfect means: from a point in past up to the present moment.
2004
I was a kid
Last year
November
Experiences
I've never read this book.
Future possibility
Negative
Negatives
We've never ever heard about this guy.
Superlatives
It's the most dangerous thing I've ever done.
The best
The worst
Questions
Have you ever eaten snail?
Experiences
Mostly used in questions and negatives.
Questions
Have they arrived yet?
Negatives
I haven't seen this movie yet.
Uncompleted Actions
She hasn't finished her homework yet.
Earlier than planned
Present result
No Need to Repeat
Very Recent
I've just finished it.