Overview of perfect tenses

  Simple Continuous
Present Perfect I have worked I have been working
Past Perfect I had worked I had been working
Future Perfect I will have worked I will have been working

All perfect tenses link two points in time. They show actions before a particular time in the present, past or future.

1. Present perfect

a. The Present perfect links actions in the past to the present.

This can happen in a number of ways:

the action is not finished, but continues into the present.
We have lived here all our lives (=and we still live here now)
the action took place in a period of time which is not finished.
We've all been ill this year. (=this year is not finished)
I've been to Italy several times. (=in my life)
the action happened very recently and still "news".
They've just had a baby.
the results of a past action are still important now.
I've lost my mobile phone!

b. If you relate the action to a past time you must use the Past simple.
I first met John when I was twenty-one. 
I first met John in 2014.

c. The Present Perfect is often found with these time phrases:
this month/morning/week

2 Past Perfect

The Past Perfect links a point in the past with a time further in the past.
It describes actions that happened "before the past".
She had been ill for some time before she died.
When I got home the cat had escaped.

a. Many of the time phrases often used with the Present Perfect are also used with the Past Perfect.
Had you ever seen the man before that night?
Mary hadn't been abroad for many years.

b. Other common phrases often used with the Past Perfect are:
by + past time phrases
By eight o'clock last night, they had managed to clear all the roads.
Clauses with by the time, when, etc.
The party had finished by the time I arrived.
We went on holiday when we'd finished our exams.
Notice that when we use before and after, the order of events is obvious, so the Past perfect is not always necessary and we use Simple Past.
I remembered to lock up before I went to bed.

3. Future Perfect
The Future Perfect links two actions or times in the future.
We use the Future Perfect when we look forward to a time in the future and then think about something that will be completed before that time. It is often introduced with by + future time phrase.
Come over about ten. We'll have eaten by then.
By the time I'm fifty, I hope I'll have earned enough money to retire.

Notice the word order of Future perfect questions.
Will you have finished by tomorrow?

More about the Present Perfect Simple and Continuous
1. What they have in common
Both the Present perfect simple and the Present perfect continuous link the past and the present as described above.
Sometimes there is no important difference in meaning between the two.
He's been living here for a long time.
He's lived here for a long time.

However, in most cases there are differences in emphasis which mean we choose a particular form:

a. Compare "long"/repeated action and "a moment"
If an action lasts only for a moment or a very short time, the Present perfect simple form is used. The continuous form of the Present Perfect emphasises that the action continues for a period of time, or was repeated.
Oh no! I've broken my glasses! (=lasts only for a moment)
Be careful! It's been snowing (=lasts some time)
I've been phoning all my friends to tell them the news (I've made several calls)

b. Compare "complete" actions and "incomplete" actions
If we see the action as completed, we tend to use the simple form. The continuous form emphasises that the action is incomplete, or we could continue it later.
I've done my homework. Can I go out now? (=completed)
He's been working on his assignment. (=it's not necessarily finished)

c. Activities and results
The continuous form often describes an activity. It answers the question "How have you spent your time?" We use the simple form when we emphasise the result of an activity. It answers the question "What have you achieved?"
A. What have you been doing today?
B. I've been mending my bike. (=interested in activity)
A. What have you done today?
B. I've fixed my bike! (=interested in result)
If you give a number, the simple form is always used because we are emphasising completion/results.
I've been to the gym three times this week.
I've sent fifteen e-mails so far today.

2. State verbs
Remember that some verbs describe states and are therefore not usually used in the continuous form.