Once you know the difference between an independent clause and a dependent (or subordinate) clause, you can see the basic structure of each sentence. This page will teach you a few labels you can use to describe the various combinations of independent and dependent clauses.
Some teachers think these labels are essential. We disagree. The main thing is to know that clauses can be combined in some rather complex ways.
A simple sentence consists of just one independent clause:
Mary had a little lamb.
A compound sentence consists of two independent clauses. These can be joined by a coordinating conjunction or a punctuation mark such as a semi-colon, colon, or dash:
Mary had a little lamb | and | its wool was white as snow.
Mary had a little lamb | ; | its wool was white as snow.
Mary had a little lamb | — | she kept it for its wool.
A complex sentence consists of one independent clause and any number of dependent clauses:
Wherever Mary went, | the lamb would go as well.
In this example, the first clause is dependent and the second is independent.
Finally, a compound-complex sentence consists of two independent clauses and any number of dependent clauses:
Although the children loved the lamb, | the teacher disapproved of lambs | so | she told Mary to take it home.
In this example, the first clause is dependent, whereas the last two (joined by a coordinating conjunction) are independent.