A conjunction is a word that joins other words, phrases, or clauses together — words like and, but, because, and although. English has three types: coordinating conjunctions (the seven FANBOYS: for, and, nor, but, or, yet, so), which link elements of equal weight; subordinating conjunctions (because, although, if, when…), which attach a dependent clause to a main one; and correlative conjunctions (either…or, neither…nor, not only…but also), which work in matched pairs.
The three types of conjunction
Coordinating conjunctions (FANBOYS)
Coordinating conjunctions join two elements of equal grammatical rank — two words, two phrases, or two independent clauses. There are exactly seven of them, and the acronym FANBOYS lists every one:
- For — gives a reason (roughly "because"): She left early, for she was exhausted.
- And — adds: bread and butter.
- Nor — adds a second negative: He doesn't smoke, nor does he drink.
- But — contrasts: small but powerful.
- Or — offers an alternative: tea or coffee.
- Yet — contrasts (like "but"): simple yet effective.
- So — shows a result (like "therefore"): It rained, so we stayed in.
Punctuation depends on what the conjunction joins. When it links two independent clauses (each could stand alone as a sentence), put a comma before it: The train was late, so I missed the meeting. When it only joins two words or phrases, no comma is needed: fish and chips, not fish, and chips.
Subordinating conjunctions
A subordinating conjunction introduces a dependent (subordinate) clause — one that cannot stand on its own — and links it to the main clause. Common ones include because, although, since, unless, while, if, when, before, after, as, until, though, whereas, and even though. They typically signal cause, condition, time, or contrast.
- Cause: We cancelled the picnic because it was raining.
- Condition: If you heat ice, it melts.
- Contrast: Although she was tired, she finished the race.
- Time: Call me when you land.
Word order controls the comma. If the subordinate clause comes first, follow it with a comma: Because it was raining, we cancelled the picnic. If the main clause comes first, you usually don't need one: We cancelled the picnic because it was raining.
Correlative conjunctions
Correlative conjunctions come in matched pairs that work together to connect balanced elements. The main ones are both…and, either…or, neither…nor, not only…but also, whether…or, and as…as.
- Either we leave now or we miss the flight.
- She is not only a doctor but also a novelist.
- Neither the players nor the coach was happy.
The golden rule with correlatives is parallel structure: whatever grammatical form follows the first half must be matched after the second. ✓ She wants both to travel and to write. ✗ She wants both to travel and writing.
Comma rules with conjunctions at a glance
- ✓ Two independent clauses + a FANBOYS word → comma before the conjunction: I cooked, and he cleaned.
- ✗ Two words or phrases → no comma: I cooked and cleaned.
- ✓ Subordinate clause first → comma after it: When he arrived, we ate.
- ✓ Main clause first → usually no comma: We ate when he arrived.
Correct vs. incorrect examples
- ✓ I wanted to help, but I had no time. ✗ I wanted to help, I had no time. (The second is a comma splice — two full sentences joined by only a comma. Add a conjunction or use a semicolon.)
- ✓ It was late, so we went home. ✗ It was late we went home. (Two sentences fused with no link is a run-on; a coordinating conjunction repairs it.)
- ✓ Neither the letters nor the parcel has arrived. ✗ Neither the letters nor the parcel have arrived. (With neither…nor, the verb agrees with the nearer subject — here the singular parcel.)
- ✓ He is not only talented but also humble. ✗ He is not only talented but he is also humble. (Keep the two halves parallel.)
- ✓ Although it was late, we kept working. ✗ Although it was late we kept working. (A subordinate clause at the front needs a following comma.)
Tricky cases and myths
Conjunctive adverbs are not conjunctions
Words like however, therefore, moreover, nevertheless, and consequently feel like conjunctions, but they are actually conjunctive adverbs. They cannot join two independent clauses with a comma alone — doing so creates a comma splice. Use a semicolon (or a full stop) instead: ✓ It was expensive; however, we bought it. ✗ It was expensive, however, we bought it.
You can start a sentence with a conjunction
The old rule that you must never begin a sentence with and, but, or because is a myth. Respected authorities — including the Chicago Manual of Style and Merriam-Webster — confirm that opening with a coordinating conjunction is standard, and skilled writers have done it for centuries. Use it for deliberate emphasis, not in every sentence. A sentence starting with because is fine too, as long as it also contains a main clause: Because we planned ahead, everything ran smoothly.
"Than" and "as": conjunction or preposition?
Traditional grammar treats than as a conjunction, which is why formal writing prefers She is taller than I (am) over than me. In everyday speech, than me is extremely common and widely accepted. Both are understood; the pronoun form (than I) is the safer choice in formal contexts.
A quick memory trick
For the seven coordinating conjunctions, remember FANBOYS: For, And, Nor, But, Or, Yet, So. For correlatives, remember that they always travel in pairs — once you write the first half (either, neither, not only), your reader is already waiting for the second (or, nor, but also).
US vs. UK differences
Conjunction grammar is nearly identical on both sides of the Atlantic, but two points genuinely differ. First, the serial (Oxford) comma — the comma before the final and or or in a list — is standard in most American style guides (red, white, and blue) and often dropped in British writing (red, white and blue), even though the name comes from Oxford University Press. Second, different than, where than functions as a conjunction (It's different than I expected), is accepted in American English, whereas British English prefers different from or different to.
