Theorie:

Study the information below to find out when to put a comma.
  
1. There are two types of relative clause.

Type 1

The woman who lives next door is a doctor.

We stayed at the hotel that you recommended.

The relative clause tells you which person or thing the speaker means.

‘The woman who lives next door’ tells us which woman.

We don’t use a comma (,) in these clauses:

We know a lot of people who live in Canada.
  
 
Type 2

My brother Bob, who lives in Australia, is a vet.
  
We stayed at the Park Hotel, which a friend of ours recommended.
  
hotel-exterior.jpg

Here the relative clauses do not tell you which person or thing the speaker means.

These relative clauses give use extra information about the person or thing.

We use a comma (,) in these clauses.
 
 
Quellen:
www.tripadvisor.co.uk
www.pond5.com