A coordinating conjunction is a short word that joins two equal grammatical units — words, phrases, or independent clauses. English has exactly seven of them: for, and, nor, but, or, yet, so. The acronym FANBOYS is a common way to remember all seven.
The key idea is equal. A coordinating conjunction connects a noun to a noun, a verb to a verb, a clause to a clause — never a main clause to a dependent one. That job belongs to a different type of conjunction, covered separately.
And
And adds one element to another.
When and joins two verbs that share the same subject, the result is a single sentence with no comma needed.
But
But introduces a contrast — what follows goes against what came before.
But often connects short opposites: cheap but good, tired but happy, simple but effective.
Or
Or offers a choice or an alternative.
In the last example, or connects two independent clauses and carries a slight warning: if the first thing doesn't happen, the second one will.
So
So shows a result — the second part happens because of the first.
Notice the pattern: cause first, then so, then consequence.
Yet
Yet works like but with more surprise. The contrast feels unexpected or even contradictory.
In everyday speech, but is far more common. Yet appears more often in writing and slightly formal contexts.
For
For gives a reason, much like because. It sounds formal and is rare in conversation.
In modern English, most people would use because instead. You'll mainly see for in written or literary language. When you do encounter it, the meaning is always "the reason is that..."
Nor
Nor adds a second negative after a first one. It often pairs with neither, but it can also follow any negative clause.
After nor, the word order in a clause flips — the auxiliary verb comes before the subject: nor does she, nor did he, nor will they. Correlative pairs like neither...nor are covered separately.
What coordinating conjunctions can join
These seven words work at three levels.
Words. Two nouns, two adjectives, two verbs, two adverbs — any pair of the same type.
Phrases. Groups of words that function as a single unit.
Independent clauses. Complete sentences joined into one.
The comma rule
When a coordinating conjunction joins two independent clauses — each one could be a sentence on its own — place a comma before the conjunction.
When a conjunction joins two words or phrases rather than full clauses, no comma is needed.
A simple test: look at what comes after the conjunction. If it has its own subject and verb and could stand alone as a sentence, use a comma. If it couldn't, don't.
Common mistakes
Missing comma before a conjunction between clauses
Unnecessary comma between words or phrases
Wrong conjunction for the meaning
Word order after nor
Using two conjunctions for one connection