A coordinating conjunction is a word that joins two elements of equal grammatical rank and syntactic importance. They can join two verbs, two nouns, two adjectives, two phrases, or two independent clauses. The seven coordinating conjunctions are for, and, nor, but, or, yet, and so.
Meet the key players: FANBOYS
The best way to remember the seven coordinating conjunctions is by using the acronym FANBOYS:
For And Nor But Or Yet So
Of these seven, so can be used as both a coordinating conjunction and a subordinating conjunction. As a coordinating conjunction, so can link two independent clauses in a manner similar to therefore, and as a subordinating conjunction, it can link two unequal clauses (one independent clause and one dependent clause) in the sense of so that.
Conjunctions that connect two words
Coordinating conjunctions can join two verbs . . .
. . . two nouns . . .
. . . two adjectives . . .
. . . two adverbs . . .
. . . or any two words with the same syntactical value. And and or can also be used to join the final two elements in a series, with commas separating the rest of the elements.
Whether or not you place a comma before the and or or is a matter of stylistic choice. When you do put a comma before the final conjunction in a series, it is referred to as a “serial comma” or an “Oxford comma.” Despite the fact that it is recommended by the Oxford University Press style manual, most writers of British English do not use it. In the United States, however, it is quite common. It is arguable that when writing in American English, using the serial comma is the best choice because it eliminates any possibility of ambiguity and creates order for the reader. If your English teacher was of a certain age, you may believe that it is not acceptable to place a comma before words like and, but this has no true grammatical basis.
Conjunctions that connect two phrases
The rules for using coordinating conjunctions to join grammatically equal phrases are the same.
Conjunctions that connect two clauses
Coordinating conjunctions, a.k.a. the FANBOYS, can connect two independent clauses. Independent clauses are so called because each of them can stand on its own as a sentence. We connect them with FANBOYS, however, so that we don’t spit out all our sentences like robots.
I know they are not good for me.
My brother has told me this.
I don’t want to listen.
Coordinating conjunctions make these ideas sound more fluent.
When joining two clauses with a coordinating conjunction, always place a comma before the conjunction.
Can you start a sentence with a coordinating conjunction?
Perhaps your teacher taught you that you should never start a sentence with the FANBOYS. But the truth is, you can. (I just did.) The reason your teacher may have taught you this was to discourage you from writing sentence fragments. Once you are past that developmental stage, however, there is no reason why you can’t start a sentence with a conjunction. Let’s vary the examples above.
Just remember not to overuse these kinds of sentences, because too many of them can sound punchy.
You might be thinking, “Wait! I know I’ve seen words other than the FANBOYS joining two independent clauses before. When will these words be given the grammatical recognition that they deserve?” Don’t worry, because that moment is now. The words you are thinking of do function similarly to coordinating conjunctions, but they are classified as conjunctive adverbs. Some examples of conjunctive adverbs are however, moreover, namely, nevertheless, meanwhile, subsequently, and furthermore.