Conjunctions
Learn how conjunctions join words, phrases and clauses, and how the three types of conjunctions are used differently.
Joining ideas together
A conjunction connects two or more parts of a sentence.
A conjunction joins words, phrases or clauses together. Without conjunctions, ideas that belong together would have to stand as separate, disconnected sentences.
In the sentence She wanted to stay, but she had to leave., the word but is a conjunction. It joins two complete ideas and shows that they are in contrast with one another.
This page covers the three types of conjunctions, the punctuation each one requires, and how the choice of conjunction changes the relationship between the ideas it connects.
The central idea
A conjunction can join equal parts, or unequal parts.
Compare a conjunction joining two equal ideas with one joining a main idea to a supporting one.
01
Equal parts
Joins two ideas that could each stand alone.
She cooked, and he cleaned.
02
Unequal parts
Joins a main idea to one that depends on it.
She left because it was late.
The useful question is: could both parts stand alone as sentences?
If both parts could stand alone, the conjunction is likely coordinating. If one part depends on the other to make sense, the conjunction is likely subordinating.
Coordinating conjunctions
Seven conjunctions join equal elements.
These seven words are often remembered using the acronym FANBOYS: for, and, nor, but, or, yet, so.
for — gives a reason: He stayed home, for he was unwell.
and — adds information: She packed her bag and left.
nor — adds a negative alternative: He does not cook, nor does he clean.
but — shows contrast: The film was long, but it was interesting.
or — shows a choice: You can call, or you can email.
yet — shows an unexpected contrast: She was tired, yet she kept working.
so — shows a result: It started raining, so they went inside.
A comma comes before the conjunction
The train was delayed, so we arrived late.
When a coordinating conjunction joins two independent clauses, each of which could stand alone as a complete sentence, a comma is placed before the conjunction.
Subordinating conjunctions
These conjunctions attach a dependent idea to a main one.
A subordinating conjunction introduces a clause that cannot stand alone as a complete sentence, and connects it to a main clause that can.
Time or condition
Because it was raining, they cancelled the trip.
Common words: because, since, if, unless, when, while, although.
The dependent clause can move
They cancelled the trip because it was raining.
The same idea can be expressed with the dependent clause at the end of the sentence instead of the beginning.
A comma is used only when the dependent clause comes first
Because it was raining, they cancelled the trip.
When the sentence begins with the main clause instead, no comma is needed before the subordinating conjunction.
Correlative conjunctions
These conjunctions work in matching pairs.
either…or — Either you call her, or I will.
neither…nor — She is neither late, nor early.
both…and — He is both talented and hardworking.
not only…but also — She is not only a teacher, but also a writer.
Each part of the pair introduces a matching structure
She is not only a teacher but also a writer.
The words that follow each part of the pair should match in form: a noun following the first part is matched by a noun following the second.
A practical decision guide
Ask these questions before choosing a conjunction.
01
Could both parts stand alone as sentences?
If so, a coordinating conjunction is likely the right choice.
02
Does one part depend on the other?
If so, a subordinating conjunction connects them.
03
Is the dependent clause first or second?
A comma is used only when the dependent clause comes first.
04
Are two conjunctions working together as a pair?
Check that the words following each part of the pair match in form.
Common errors
Mistakes are useful when you understand why they happen.
The train was delayed so we arrived late.
The train was delayed, so we arrived late.
A comma is needed before a coordinating conjunction that joins two independent clauses.
They cancelled the trip, because it was raining.
They cancelled the trip because it was raining.
When the main clause comes first, no comma is placed before the subordinating conjunction.
She is not only a teacher but also writing.
She is not only a teacher but also a writer.
The word following each part of a correlative pair should match in form.
Because it was raining. They cancelled the trip.
Because it was raining, they cancelled the trip.
A clause that begins with a subordinating conjunction cannot stand alone as a complete sentence.
Your turn
Practise choosing and punctuating conjunctions.
These activities are part of the learning process. There are no scores, no grades and no limit on how many times you may try.
Which sentence uses the comma correctly?
? Exactly! Both parts are independent clauses, so a comma comes before but.
? Not quite. Check whether both halves of the sentence could stand alone.
Could “they went outside” stand alone as a sentence?
Which sentence is punctuated correctly?
? Exactly! A comma follows the dependent clause when it comes first.
? Not quite. The dependent clause comes before the main clause here.
Which clause comes first, the dependent one or the main one?
Which sentence uses the correlative pair correctly?
? Exactly! Neither is paired with nor, not or.
? Not quite. Neither requires its matching pair, nor.
Correlative conjunctions come in fixed pairs.
Quick review
Three types of conjunctions join ideas in different ways.
Coordinating conjunctions (FANBOYS: for, and, nor, but, or, yet, so) join two equal, independent ideas, with a comma placed before the conjunction.
Subordinating conjunctions, such as because, although and if, connect a dependent clause to a main clause; a comma is used only when the dependent clause comes first.
Correlative conjunctions work in matching pairs, such as either…or and not only…but also, and require matching forms on both sides of the pair.
Remember
Ask what relationship the conjunction is showing.
A conjunction does more than join words together; it tells the reader how the two ideas relate, whether that is addition, contrast, choice, cause or condition.