– Expresses an action that started in the past.
– The action is still going on, or has recently stopped, but still has an influence on the present.

Form : 
•Positive
Subject + have/has + past participle

•Negative
Subject + have/has + not/n’t + past participle

•Question 
Have/has + subject + past participle

Uses :
1. Remember, the present perfect is an action that started in the past, but is still relevant to the present.

e.g.
Tom has broken his leg ⇒ He broke it in the past and can’t use it now.

2. An action in the past that is still happening regularly.

e.g.
They have done gymastics at this club since 2010 ⇒ They started in 2010, and they still do it.

3. Actions that were repeated several times in the past.
e.g.
I’ve already gone to this restaurant 5 times ⇒ He has been several times in the past, and the date isn’t important.

Time expressions with the present perfect : 
NEVER use the same time expressions that you use in the past simple tense, such as :
Yesterday ⇒ Yesterday I went to the park. (past simple)
Last night ⇒ Last night I spoke to my boyfriend. (past simple)
A week ago ⇒ A week ago I was in Greece. (past simple)

You can only use UNSPECIFIC time expressions, such as
Since ⇒ Since 2013 I have lived in London. (Present perfect)
Never ⇒ I have never visited Burma. (Present perfect)
Already ⇒ They have already finished their homework. (Present perfect)
So far ⇒ So far I have not had a problem with them. (Present perfect)