What Is a Conjunction? Types, Rules, and Examples

A conjunction is a word that connects words, phrases, or clauses within a sentence. Without conjunctions, our speech and writing would consist entirely of short, choppy sentences: "I was tired. I kept working." With a conjunction, those become a flowing compound sentence: "I was tired, but I kept working." Conjunctions are the glue of English grammar—they create relationships between ideas, showing whether concepts are additive, contrasting, causal, or conditional. This guide covers all three types of conjunctions, their rules, punctuation requirements, and the common mistakes writers make when using them.

Conjunction Definition

The word "conjunction" comes from the Latin conjunctio, meaning "a joining together." That captures their role perfectly—conjunctions join linguistic elements together. They are one of the eight traditional parts of speech and, like prepositions, are a "closed class"—new conjunctions are rarely if ever created.

Conjunctions express logical relationships: addition (and), contrast (but), cause (because), condition (if), choice (or), time (when, before, after), and more. The conjunction you choose tells the reader exactly how two ideas relate, which is why mastering conjunctions is essential for clear, well-structured writing.

Coordinating Conjunctions (FANBOYS)

Coordinating conjunctions connect grammatically equal elements—words to words, phrases to phrases, clauses to clauses. There are seven, remembered by the acronym FANBOYS:

"And" is by far the most common conjunction in English—it is one of the ten most frequently used words in the language. "But" and "or" complete the top three. These seven small words are responsible for joining an enormous percentage of the clauses and phrases in English.

Connecting Words and Phrases

"She ordered soup and salad." — Joins two nouns.
"The house was old but charming." — Joins two adjectives.
"He ran quickly and efficiently." — Joins two adverbs.

Connecting Independent Clauses

When a coordinating conjunction joins two independent clauses, place a comma before it:

"The alarm rang, and everyone evacuated the building."
"She studied all night, yet she still felt unprepared."

Subordinating Conjunctions

Subordinating conjunctions connect an independent clause to a dependent (subordinate) clause, creating complex sentences. They establish relationships of time, cause, condition, contrast, and purpose:

Time

when, while, before, after, since, until, as soon as, once, whenever

"After the rain stopped, we went for a walk."
"She has worked here since she graduated."

Cause and Reason

because, since, as, now that, given that

"Because the road was icy, we drove slowly."
"Since you asked, I'll explain."

Condition

if, unless, provided that, as long as, in case, even if, whether

"If it rains, the event will be moved indoors."
"We'll proceed unless there are objections."

Contrast and Concession

although, though, even though, whereas, while

"Although she was tired, she finished the project."
"He prefers coffee, whereas she prefers tea."

Purpose

so that, in order that, lest

"She left early so that she could avoid traffic."

Correlative Conjunctions

Correlative conjunctions work in pairs, connecting balanced elements:

• both...and — "Both the coach and the players celebrated."
• either...or — "You can either stay or leave."
• neither...nor — "Neither the proposal nor the budget was approved."
• not only...but also — "She is not only intelligent but also creative."
• whether...or — "I don't know whether to laugh or cry."
• as...as — "She is as talented as her predecessor."

The key rule for correlative conjunctions is parallel structure: the grammatical element following the first conjunction must match the element following the second. "She not only sings but also dances" (two verbs) is correct. "She not only sings but also a good dancer" (verb + noun phrase) violates parallelism.

Conjunctive Adverbs

Though technically adverbs, conjunctive adverbs function similarly to conjunctions by showing the logical relationship between independent clauses: however, therefore, moreover, furthermore, nevertheless, consequently, meanwhile, otherwise, instead, similarly, accordingly.

Conjunctive adverbs are punctuated with a semicolon before and a comma after:

"The data was inconclusive; therefore, we extended the study."
"The first experiment failed; however, the team remained optimistic."

Conjunction Punctuation Rules

1. Coordinating conjunctions joining independent clauses: Use a comma before the conjunction. "She called, and he answered."
2. Coordinating conjunctions joining words or phrases: No comma needed. "Coffee and tea." "Fast but accurate."
3. Subordinating conjunctions at the beginning: Use a comma after the dependent clause. "Because it was late, we left."
4. Subordinating conjunctions in the middle: Usually no comma needed. "We left because it was late."
5. Oxford comma: In lists of three or more items, the comma before the final "and" (the Oxford comma) is recommended for clarity: "We need bread, milk, and eggs."

Can You Start a Sentence with a Conjunction?

Yes. The "rule" against starting sentences with "and," "but," or "because" is a myth with no basis in English grammar. Every major style guide, from the Chicago Manual of Style to Strunk and White, acknowledges that starting sentences with conjunctions is perfectly acceptable and has been practiced by the finest English writers for centuries.

"The expedition faced countless obstacles. But they persevered." The conjunction creates emphasis and a dramatic pause that a comma-joined compound sentence would not.

"And so it began." Starting with "and" can create a sense of continuation and narrative momentum.

Use this technique deliberately for effect—not habitually, which can make prose feel fragmented.

Creating Compound Sentences

Coordinating conjunctions are the primary tool for creating compound sentences—sentences with two or more independent clauses:

"The storm approached rapidly, and the residents prepared for the worst."
"She could fly to Madrid, or she could take the overnight train."

Compound sentences create balance and show the relationship between equally important ideas. They are a key element of sentence variety.

Creating Complex Sentences

Subordinating conjunctions create complex sentences by making one clause dependent on another:

"When the meeting ended, everyone hurried to lunch." — The "when" clause is dependent; it cannot stand alone.
"The project succeeded because the team collaborated effectively."

Complex sentences allow writers to show hierarchical relationships between ideas—which idea is the main point and which provides supporting context.

Parallel Structure with Conjunctions

When conjunctions connect two or more elements, those elements should be grammatically parallel:

Correct: "She likes swimming, hiking, and cycling." (Three gerunds.)
Incorrect: "She likes swimming, to hike, and cycling." (Mixed forms.)

Correct: "The report was thorough, accurate, and timely." (Three adjectives.)
Incorrect: "The report was thorough, accurate, and delivered on time." (Two adjectives + a verb phrase.)

Parallel structure creates rhythm, clarity, and elegance. It is one of the hallmarks of polished writing.

Common Conjunction Mistakes

1. Comma splice: Using a comma without a conjunction between independent clauses. "It was late, we left" should be "It was late, so we left" or "It was late; we left."
2. Run-on sentence: Joining independent clauses with no punctuation or conjunction. "It was late we left" needs a conjunction or proper punctuation.
3. Misusing "because": "The reason is because..." is redundant. Use "The reason is that..." or simply "Because..."
4. Broken parallelism: "She likes reading and to write" should be "She likes reading and writing."
5. Double conjunction: "Although she was tired, but she kept working" uses both a subordinating and coordinating conjunction. Use one: "Although she was tired, she kept working" or "She was tired, but she kept working."

Practice Exercises

Identify the conjunction type in each sentence:

1. "She studied hard, yet she didn't pass." — Coordinating (yet).
2. "Because the weather improved, the event was held outdoors." — Subordinating (because).
3. "Both the teachers and the students attended the assembly." — Correlative (both...and).
4. "He was talented; moreover, he was hardworking." — Conjunctive adverb (moreover).
5. "I'll go if you go." — Subordinating (if).

Conjunctions are the joints that hold the skeleton of English together. Master them, and you master the ability to express complex, nuanced relationships between ideas. For more grammar resources, visit dictionary.wiki and explore our English grammar basics guide.