A clause is a port of a sentence. There are two main
types independent (main clauses), dependent
(subordinate).
We use non-defining relative clauses to give essential information
Relative Clauses
Defining relative clauses (also called identifying
relative clauses or restrictive relative clauses)
give detailed information defining a general
term or expression. Defining relative clauses are
not put in commas.
I told about the woman who lives netx door.
Non-Defining
clauses
Non-defining relative clauses (also called
non-identifying relative clauses or non-restrictive
relative clauses) give additional information on
something, but do not define it. Non-defining
relative clauses are put in commas.
Clare, who i work whith, is doing the London marathon this year-