Adjective clauses are dependent clauses that begin with who, which, or that and follow and describe a noun. Commas are used to set off adjective clauses that provide extra, non-essential information about the noun, while no comma is needed if the adjective clause gives necessary information about the noun. Examples are given of sentences with adjective clauses both with and without commas.

1. Abdul Aziz Assanosi
azizsanosi@gmail.com
Main Source:
First Steps in Academic Writing (Level 2)
Second Edition
By: Ann Hogue
Pearson Longman

2. 
Adjective clauses are kind of
(DEPENDENT CLAUSES) DCs.
Adjective clauses

3. 
That man, who wears a uniform, is my
friend.
Jeddah, which lies on the seacoast, is
called the bride of the red sea.
A train which goes in tunnels is called
subway train.
Examples

4. 
Adjective clauses begin with who,
which, or that.
They always follow the noun they
describe
Note that…

5. 
We use commas when the adjective clauses
present extra information:
My friend, who is standing there, is funny.
Apple company, which is a big company, is
in USA.
Wild animals, that live in wilderness, are
dangerous
Comma usage

6. 
If the adjective clause give necessary
information about the noun we don’t use
commas.
All students who studies hard get an A
grade.
Computers which have flip top are called
laptops.
A butcher is a man who sells meat.
No comma needed