A clause is a unit of grammar that expresses a proposition. In other words, it is part of a sentence that contains some form of meaning.
Although there was a storm, I walked to work.
Here, there are two clauses. “Although there was a storm” expresses a proposition, and so does “I walked to work.”
The first clause in the example above is called an adverb clause, which means that it is part of a sentence that contains a subordinating conjunction, a subject, and a verb. There are essentially five types of adverb clauses, and they can use a variety of subordinating conjunctions. They are:
Place – wherever, anywhere, everywhere, where
Example: Everywhere she goes, she brings a camera.
Time – since, while, as soon as, before, after, until, when, anytime
Example: While we were waiting for the pizza guy to arrive, we played poker at the kitchen table.
Reason – because, since, as, for, so that
Example: Because it was exceptionally cold, I wore my winter jacket.
Condition – if, when, unless, even if, even though
Example: Even if they lose by five goals, people will still love them.
Contrast – though, although, despite, in spite of, whereas
Example: Despite the poor service provided by the wait staff, we still enjoyed the food and the atmosphere of the restaurant.
All of these examples contain two parts: a subordinate clause (the adverb clause), and an independent clause. A subordinate clause needs an independent clause for it to have a complete context and for it to make sense.
The subordinate clause and independent clause can be reversed in a sentence. However, if the subordinate clause comes first, there must be a comma between it and the independent clause.
Example: Anytime I want to go outside, it always seems to rain.
This sentence can also be flipped, so that the independent clause comes first. However, if the independent clause comes first, a comma is not necessary.
Example: It always seems to rain anytime I want to go outside.
Adverb clauses are an important part of spoken and written English, and must be understood if a student wants to be a fluent speaker, or a better writer.