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Conjunctions are the connecting words that join words, phrases, and clauses together. Without conjunctions, English would be a series of short, choppy, disconnected sentences. Conjunctions create relationships between ideas — addition, contrast, cause and effect, time sequence, and more — making it possible to express complex thoughts clearly and efficiently.
This guide covers the three main types of conjunctions, their punctuation rules, and the most common errors writers make when using them.
What Are Conjunctions?
A conjunction is a part of speech that connects words, phrases, or clauses. The word "conjunction" comes from Latin conjungere, meaning "to join together." English has three types of conjunctions, each serving a different function:
- Coordinating conjunctions join equal elements.
- Subordinating conjunctions join a dependent clause to an independent clause.
- Correlative conjunctions work in pairs to join equal elements.
Coordinating Conjunctions (FANBOYS)
Coordinating conjunctions join elements of equal grammatical rank: two words, two phrases, or two independent clauses. There are only seven, remembered by the acronym FANBOYS:
| Conjunction | Function | Example |
|---|---|---|
| For | Reason/cause | She left early, for she was feeling ill. |
| And | Addition | She bought apples and oranges. |
| Nor | Negative addition | He neither called nor wrote. |
| But | Contrast | She is tired but happy. |
| Or | Alternative | Would you like tea or coffee? |
| Yet | Contrast/surprise | It is small yet powerful. |
| So | Result/consequence | It rained, so we stayed inside. |
Key Rules for Coordinating Conjunctions
- When joining two independent clauses, place a comma before the conjunction: "She studied hard, but she failed the test."
- When joining two words or phrases (not independent clauses), no comma is needed: "She studied hard but failed the test."
- In a list of three or more items, use commas between items and (optionally) before the final conjunction: "apples, oranges, and bananas."
Subordinating Conjunctions
Subordinating conjunctions introduce dependent (subordinate) clauses and connect them to independent clauses. They create relationships of time, cause, contrast, condition, and more.
Common Subordinating Conjunctions by Category
| Category | Conjunctions |
|---|---|
| Time | after, before, when, while, until, since, as, as soon as, once, whenever |
| Cause/Reason | because, since, as, now that, in order that |
| Contrast/Concession | although, though, even though, whereas, while, even if |
| Condition | if, unless, provided that, as long as, in case, whether |
| Purpose | so that, in order that, so as to |
| Comparison | as, as if, as though, than |
| Place | where, wherever |
Examples
- "Because it was raining, we stayed inside."
- "She left before the movie ended."
- "Although he was tired, he kept working."
- "I'll help you if you ask nicely."
- "While she studied, he watched TV."
- "We waited until the storm passed."
Punctuation Rule
When the dependent clause comes first, follow it with a comma: "Because it was raining, we stayed inside." When the independent clause comes first, a comma is usually unnecessary: "We stayed inside because it was raining."
Correlative Conjunctions
Correlative conjunctions work in pairs to join equal grammatical elements. They must connect parallel structures — the same type of word, phrase, or clause on each side.
| Pair | Function | Example |
|---|---|---|
| both...and | Addition (emphasis) | She is both talented and hardworking. |
| either...or | Choice | Either you come with us, or you stay here. |
| neither...nor | Negative choice | He neither smokes nor drinks. |
| not only...but also | Emphatic addition | She is not only smart but also kind. |
| whether...or | Choice/alternative | Whether you like it or not, we are going. |
| as...as | Comparison | She is as tall as her brother. |
| such...that | Result | It was such a good book that I read it twice. |
| so...that | Result | She was so tired that she fell asleep instantly. |
Parallel Structure with Correlative Conjunctions
The elements joined by correlative conjunctions must be grammatically parallel:
- Wrong: "She not only likes reading but also to swim."
- Right: "She not only likes reading but also likes swimming." (Or: "She likes not only reading but also swimming.")
Conjunctive Adverbs
While not technically conjunctions, conjunctive adverbs function similarly by connecting independent clauses and showing the relationship between them. They differ from conjunctions in their punctuation: they require a semicolon before them and a comma after.
- however, nevertheless, nonetheless (contrast)
- therefore, consequently, thus, hence (cause/effect)
- furthermore, moreover, additionally (addition)
- meanwhile, subsequently (time)
- instead, otherwise (alternative)
- for example, for instance (example)
Example: "The experiment failed; however, the team learned valuable lessons."
Punctuation with Conjunctions
| Situation | Punctuation | Example |
|---|---|---|
| Coordinating conjunction + 2 independent clauses | Comma before conjunction | She ran, but she tripped. |
| Coordinating conjunction + 2 words/phrases | No comma | She ran and tripped. |
| Subordinating conjunction at beginning | Comma after dependent clause | Because it rained, we left. |
| Subordinating conjunction in middle | Usually no comma | We left because it rained. |
| Conjunctive adverb between clauses | Semicolon before, comma after | It rained; therefore, we left. |
Can You Start a Sentence with a Conjunction?
Yes. The "rule" against starting sentences with "and," "but," or "because" is a myth. Respected writers throughout the history of English have started sentences with conjunctions. The Bible does it constantly. Shakespeare does it. Modern style guides confirm that it is perfectly acceptable.
"But" at the beginning of a sentence creates emphasis and a sense of dramatic contrast. "And" signals an addition that deserves its own sentence for emphasis. "Because" can open a sentence as long as the dependent clause is followed by a comma and an independent clause: "Because the road was icy, we drove slowly."
Common Errors
- Comma splice with conjunctive adverbs: "The test was hard, however, she passed." Use a semicolon: "The test was hard; however, she passed."
- Missing comma before coordinating conjunction: "She was tired but she kept working." Add a comma: "She was tired, but she kept working."
- Non-parallel correlatives: "He both likes to read and writing." Should be: "He likes both reading and writing."
- Sentence fragment: "Because she was tired." This is a dependent clause that needs an independent clause to complete it.
Conjunctions are the structural backbone of complex writing. They allow you to build compound and complex sentences, show relationships between ideas, and guide readers through your reasoning. Mastering the three types of conjunctions and their punctuation rules is essential for clear, sophisticated writing.