The present perfect tense is used to represent an action which has been completed within a period of time that extends up to the present. The present perfect tense can also be used to talk about actions which cannot be attributed to a definite point of time.

When the verb is transitive

The present perfect tense has the following structure: Subject + has/have + past participle form of the verb + object + adverbials/complements etc.

Have you seen him this morning?
I have never seen him before.
I have just completed my book on Hindu philosophy.
They have already paid the dues from 1990 onwards.
He has not yet returned the book he borrowed from me.
It hasn’t stopped raining since yesterday.
She has endured many hardships.
I have not yet completed my work.
She has not returned home.

When the verb is intransitive

When the verb is intransitive, there will be no object and the sentences will have the following structure:
Subject + has/have + past participle of the intransitive verb + adverbials or complements etc.

We have lived here since 1995.
We have lived here for 20 years.
You have grown enormously in the last two years.
He has already gone to the market.
I have been there this morning.

She has slept for four hours.

Notes

The present perfect is a present tense, so we cannot place the action at a point of time in the past. Consequently, adverbs referring to the past time (e.g. yesterday, last week, last year, two years ago etc.) cannot be used with the present perfect tense.  But note that a period of time extending up to the present time may be mentioned. Examples are: for two years, for a long time, since 1995, in the last two years etc. Adverbs like just, recently, already, ever, never, yet, today, this morning etc., may also be used with the present perfect tense.

Common Errors

I have written to him yesterday. (Wrong)
I wrote to him yesterday. (Right)
She has died two months ago. (Wrong)
She died two months ago. (Right)
We have lived there till 1990. (Wrong)
We lived there till 1990. (Right)

Explanation

The adverbs ‘yesterday’, ‘two months ago’ and ‘till 1990’ refer to the past time and cannot be used with the present perfect tense. If you do have to mention these adverbs use the simple past tense.