Sentence, Clause, Phrase - Division of Sentences on the Basis of Structure - COMPLEX sentences

A complex sentence is made up of an independent clause and one or more dependent clauses. Each dependent clause begins with a subordinating conjunction or a relative pronoun.

The idea expressed by the independent clause is more important than the idea expressed by the dependent clause.

For example:

I have to leave early because I have to meet someone.

This sentence can be broken up into two clauses as follows:

I have to leave early. (INDEPENDENT CLAUSE) Because I have to meet someone (DEPENDENT CLAUSE)

You can see that the independent clause can stand by itself and make its meaning clear.

However, the dependent clause—beginning with the subordinating conjunction ‘because’— cannot stand on its own and make complete sense. Since it begins with a subordinating conjunction, it is dependent upon (or subordinate to) the independent clause.

In the sentence, the idea contained in the independent clause (leave early) is more important than the idea contained in the dependent clause (meet someone).