1. Clauses
A clause is a group of words that contains a subject and a verb.

2. Independent and subordinate clauses
The two basic kinds of clauses are independent or MAIN CLAUSES and subordinate clauses.

3. Independent Clause(Main Clause)
An independent or main clause can stand by itself as a complete sentence.
Every sentence must contain an independent clause. The independent clause can either stand by itself or be connected to other independent or subordinate clauses.

4. Independent Clause Standing Alone Mr. Holden teaches history.
With another independent clause
Mr Holden teaches history, and his sister teaches math.
With a subordinate clause
Mr. Holden teaches history while his sister teaches math.

5. Subordinate Clause
When you subordinate something, you give it less importance.
A subordinate clause, although it has a subject and verb, cannot stand by itself as a complete sentence.
Subordinate clauses can appear before or after an independent clause in a sentence or can even split and independent clause.

6. Locations of Subordinate Clauses
In the middle of an Independent Clause
The man to whom I introduced you teaches history.
Preceding an Independent Clause
Unless the snow stops soon, the roads will be closed.
Following an Independent Clause
Hannah asked that she be excused.