Structure: Subject + has/have + past participle form of the verb

I have written a novel.
They have returned.
We have invited them.
He has refused to go.

The present perfect tense is used:

1) To talk about an action that has been finished just now or in the immediate past.

They have just arrived.
I have finished writing.

2. To talk about a past action that has its effect in the present.

Somebody has let the cat in. (= The cat is in now. The action took place in the past, but its effect is felt in the present.)
I have broken my arm, so I can’t do any work now. (The action took place in the past, but its effect is still felt in the present.)

3. To talk about an action that began sometime in the past, but is still continuing.

We have lived here for ten years. (We still live here.)
I have known him for a long time. (I still know him.)

4. To talk about a past action

We can use the present perfect tense to talk about a past action when it is not mentioned when the action took place.

He has helped me several times.
I have never seen a ghost.

Notes

The present perfect tense cannot be used with adverbs of past time like yesterday, last year, last week, when, then etc.

He went to Mumbai yesterday. (BUT NOT He has gone to Mumbai yesterday.)