Out of the three different kinds of conjunctions (coordinating, correlative and subordinating), subordinating conjunctions are the most difficult to recognize, but they are not that hard to master. In fact, you probably use them all the time without even noticing, but let’s take a closer look at them to see what’s going on.
A subordinating conjunction is a word that connects a main clause to a subordinate clause. A main clause is an independent clause that can stand alone by itself as a sentence. In other words, a main clause does not need any additional information to operate as a sentence. For example, the sentence "The student failed the test" is an example of a main clause.
A subordinate clause is a dependent clause that adds some extra information to the main clause. These phrases cannot stand by themselves, and their meaning is dependent upon that of the independent clause. They are not sentences! For example, "because she didn't study" is not a complete idea worthy of being defined as a sentence. However, combine the two clauses, and we have "The student failed the test because she didn't study." A complete idea has been expressed, and enough information has been presented in order to fully explain the thought.
In English, there are lots of subordinating conjunctions, but the most common ones, along with a few examples of how subordinating conjunctions are used, are as follows:
You’ll notice that when a dependent clause precedes an independent clause, there is a comma between the two, indicating the beginning of the main (independent) clause. However, when the independent clause comes first, there is no need to separate the two clauses with a comma.
As with any grammatical device, using the subordinating conjunction too much becomes repetitive and boring. Of course, certain types of writing require a bare-bones style without much comedy or flavorful tone. However, subordinating conjunctions should still be used only sparingly. Constantly using the same device does not only sound rote, but doing so also sounds like the work of an inexperienced writer. Experienced writers know that subordinating conjunctions, and other tools, should only be used when they are warranted. Writing style should never be forced, as forced writing is always painfully obvious!
There is another group of words that sometimes introduce dependent clauses. These are called relative pronouns, and although they look and act very similar to coordinating conjunctions, they are different. True relative pronouns are “that,” “who” and “which,” and they differ from subordinating conjunctions in that they act as the subject of a dependent clause whereas subordinating conjunctions do not. Subordinating conjunctions are followed by the subject of their clause. Consider a few examples:
Now that you know what subordinating conjunctions are, you can continue to use them, but now with new purpose and vigor!