A Clause is a the group of words but it is only a part of a sentence. It has a subject and a predicate, but still it does not make complete sense without the principal part of the sentence, called principal clause.
I don’t know where he lives.
We should remember God wherever we go.
He told me that he had finished his work.
Will you please tell me where you found this book?
In the above sentences, the group of words given in bold and underlined are Clauses.
Types of Clauses :
Strictly speaking, there are three kinds of Clauses.
Principal Clause (or) Main Clause (or) Independent Clause
Subordinate Clause (or) Dependent Clause
Principal Clause :
This Clause is the main part of sentence. As it contains the subject as well as the finite verb and the object, it can make complete sense itself. It does not have to depend upon any other Clause.
She wrote a letter.
She is the best girl in the class.
Coordinate Clause :
This Clause forms part of a sentence, but in rank, it is equal to the Principal Clause. However, alone it cannot form a sentence. It is connected to a principal clause by a Coordinating conjunction, through like the Principal Clause, in itself it forms a complete sense.
He gets up early in the morning and goes out for a walk.
He is poor but he is honest.
You must work hard or you can’t succeed.
In the above sentences, the group of words given in bold are Coordinate clauses.
Here the conjunction AND, BUT, OR are called Coordinating conjunctions.
Subordinate Clause :
A Subordinate Clause depends on a Main Clause for its complete meaning.
Though I am poor, I am happy.
As she was ill, she could not go to school.
Unless you work hard, you will fail.
In the above sentences, the group of words given in bold are Subordinate clauses.