Definition · Plain-language
Conjunction
A conjunction is a word that connects words, phrases or clauses — joining ideas together with words such as and, but, or, because and although.
The step most authors miss
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Coordinating conjunctions
Coordinating conjunctions join elements of equal grammatical rank — two words, two phrases or two independent clauses. There are seven, easily remembered by the mnemonic FANBOYS: for, and, nor, but, or, yet, so. "Tea or coffee" joins two nouns; "small but powerful" joins two adjectives; "She knocked, but no one answered" joins two complete clauses. When a coordinating conjunction joins two independent clauses, a comma normally comes before it. These are the most familiar conjunctions, and because they connect equals, the parts on either side could often stand alone as their own sentences.
Subordinating and correlative conjunctions
Subordinating conjunctions join a dependent clause to an independent one and show how the ideas relate — cause, time, condition or contrast. Words like because, although, since, if, when and unless make their clause unable to stand alone: "although it was late" needs a main clause to complete it. Correlative conjunctions work in matched pairs to link balanced elements: either…or, neither…nor, both…and, not only…but also. With these, the structure after each half should be parallel — "not only the design but also the data", not "not only the design but also analysed the data". Together with coordinating conjunctions, these three types cover almost all the joining work in English.
Starting sentences and common cautions
Two myths surround conjunctions. The first is that you must never begin a sentence with and or but. In fact, starting a sentence with a coordinating conjunction is perfectly acceptable and used by skilled writers for emphasis or flow; only overuse becomes a fault. The second concerns punctuation: a comma usually precedes a coordinating conjunction that joins two independent clauses, but not one that simply joins two words or phrases ("fish and chips" takes no comma). Conjunctions are also distinct from conjunctive adverbs such as however and therefore, which need a semicolon, not just a comma, when they link two clauses.
Key facts
At a glance
- Definition: a word that joins words, phrases or clauses
- Coordinating: joins equals — for, and, nor, but, or, yet, so (FANBOYS)
- Subordinating: joins a dependent clause to a main one (because, although)
- Correlative: works in pairs (either…or, neither…nor, not only…but also)
- Comma rule: before a coordinating conjunction joining two clauses
- Myth: starting a sentence with "and" or "but" is allowed
Common misconceptions
What people often get wrong
Often heard: You must never start a sentence with "and" or "but".
Actually: Beginning a sentence with a coordinating conjunction is grammatically acceptable and common in good writing. The only caution is not to overuse the effect.
Often heard: All conjunctions join elements of equal rank.
Actually: Only coordinating conjunctions do. Subordinating conjunctions make one clause dependent on another, as in "we waited because it rained", where the clauses are not equal.
Often heard: "However" and "therefore" are conjunctions you can join clauses with using a comma.
Actually: Those are conjunctive adverbs. When they link two independent clauses they need a semicolon, not a comma: "It rained; however, we left."
Going deeper
