A clause is a statement that is contained in a sentence. It can be the principal statement of a sentence or the minor statement of a sentence. A clause has a subject and a predicate and contains a finite verb.
A principal clause is one that contains the important statement of a sentence. It can usually stand sparately from the rest of the sentence and make sense by itself. Every sentence contains at least one principal clause.
When the rain came, the painters went home because they could not paint in the rain.
The statement “the painters went home” is the most important piece of information in the sentence. It is the principal clause. The other two statements are of lesser importance. One tells when the painters went home; the other tells the reason for their going. They are subordinate clauses.
A subordinate clause is one of lesser importance because it depends on some other caluse and cannot stand by itself. A subordinate clause does the work of a noun, an adjective or an adverb.
|Refer also to||:||Noun Clause