Present perfect: for & since

We use the present perfect with for and since to talk about an event which started in the past and still continues. It connects a time in the past with the present.
As a translation from the German word “seit”, these 2 words always create a link to the past..

We form the present perfect with the verb to have and the past participle of the main verb.
since – used with a definite point in time, e.g. since 2003
for – used to talk about a duration, e.g. for 2 years

I have worked at 24 Quick Logistics since 2003.
He has lived in Berlin for five years.
They have known each other since 1999.

I have not worked at Quick Logistics since 2003.
He has not lived in Berlin for five years.
They have not known each other since 1999.

Questions normally begin with the question words:
How long …?
Since when …?
and by inverting the subject and verb to have.
Since when have you worked at Quick Logistics?
How long have you lived in Berlin?
How long have you known each other?

The following short forms are used in speech and informal writing:
I have – I’ve
you have – you’ve
he has – he’s
she has – she’s
it has – it’s
we have – we’ve
you have – you’ve
they have – they’ve