In grammar, a conjunction (abbreviated CONJ or CNJ) is a part of speech that connects two words, sentences, phrases or clauses together. A discourse connective is a conjunction joining sentences. This definition may overlap with that of other parts of speech, so what constitutes a "conjunction" must be defined for each language. In general, a conjunction is an invariable grammatical particle, and it may or may not stand between the items it conjoins.
The definition may also be extended to idiomatic phrases that behave as a unit with the same single-word conjunction (as well as, provided that, etc.).
Many students are taught that certain conjunctions (such as "and", "but", "because", and "so") should not begin sentences; although authorities such as the Chicago Manual of Style state that this teaching has "no historical or grammatical foundation."
A simple literary example of a conjunction: "the truth of nature, and the power of giving interest" (Samuel Taylor Coleridge's Biographia Literaria) 
Coordinating conjunctions 
Coordinating conjunctions, also called coordinators, are conjunctions that join, or coordinate, two or more items (such as words, main clauses, or sentences) of equal syntactic importance. In English, the mnemonic acronym FANBOYS can be used to remember the coordinators for, and, nor, but, or, yet, and so. These are not the only coordinating conjunctions; various others are used, including:ch. 9:p. 171 "and nor" (British), "but nor" (British), "or nor" (British), "neither" ("They don't gamble; neither do they smoke"), "no more" ("They don't gamble; no more do they smoke"), and "only" ("I would go, only I don't have time").
Here are some examples of coordinating conjunctions in English and what they do:
- presents a reason ("He is gambling with his health, for he has been smoking far too long.").
- presents non-contrasting item(s) or idea(s) ("They gamble, and they smoke.").
- presents a non-contrasting negative idea ("They do not gamble nor do they smoke.").
- presents a contrast or exception ("They gamble, but they don't smoke.").
- presents an alternative item or idea ("Every day they gamble or they smoke.").
- presents a contrast or exception ("They gamble, yet they don't smoke.").
- presents a consequence ("He gambled well last night so he smoked a cigar to celebrate.").
Correlative conjunctions 
Correlative conjunctions work in pairs to join words and groups of words of equal weight in a sentence. There are six different pairs of correlative conjunctions:
- not only...but (also)
- neither...nor (or increasingly neither...or)
- just as...so
- You either do your work or prepare for a trip to the office.
- Not only is he handsome, but he is also brilliant.
- Neither the basketball team nor the football team is doing well.
- Both the cross country team and the swimming team are doing well.
- Whether you stay or you go, it's your decision.
- Just as many Australians love cricket, so many Canadians love ice hockey.
Subordinating conjunctions 
Subordinating conjunctions, also called subordinators, are conjunctions that conjoin an independent clause and a dependent clause. The most common subordinating conjunctions in the English language include after, although, as, as far as, as if, as long as, as soon as, as though, because, before, if, in order that, since, so, so that, than, though, unless, until, when, whenever, where, where as, wherever, and while. Complementizers can be considered to be special subordinating conjunctions that introduce complement clauses (e.g., "I wonder whether he'll be late. I hope that he'll be on time"). Some subordinating conjunctions (until and while), when used to introduce a phrase instead of a full clause, become prepositions with identical meanings.
In many verb-final languages, subordinate clauses must precede the main clause on which they depend. The equivalents to the subordinating conjunctions of non-verb-final languages such as English are either
- clause-final conjunctions (e.g., in Japanese); or
- suffixes attached to the verb and not separate words
Such languages in fact often lack conjunctions as a part of speech because:
- the form of the verb used is formally nominalised and cannot occur in an independent clause
- the clause-final conjunction or suffix attached to the verb is actually formally a marker of case and is also used on nouns to indicate certain functions. In this sense, the subordinate clauses of these languages have much in common with postpositional phrases.
In other West-Germanic languages like German or Dutch, the word order after a subordinating conjunction is different from the one in an independent clause, e.g., in Dutch want (for) is coordinating, but omdat (because) is subordinating. The clause after the coordinating conjunction has normal word order, but the clause after the subordinating conjunction has verb-final word order. Compare:
- Hij gaat naar huis, want hij is ziek. ("He goes home, for he is ill.")
- Hij gaat naar huis, omdat hij ziek is. ("He goes home because he is ill.")
Similarly, in German, "denn" (for) is coordinating, but "weil" (because) is subordinating:
- Er geht nach Hause, denn er ist krank. ("He goes home, for he is ill.")
- Er geht nach Hause, weil er krank ist. ("He goes home because he is ill.")
See also 
- Conjunctive adverb
- Conjunctive mood, sometimes used with conjunctions
- List of common English usage misconceptions
- Logical conjunction
- On a white bus
- Serial comma - the comma used immediately before a coordinating conjunction preceding the final item in a list of three or more items
- University of Chicago (2010). The Chicago Manual of Style (16th ed.). Chicago: Univ. of Chicago Press. p. 257. ISBN 978-0-226-10420-1.
- Greenblatt, Stephen (2006). The Norton Anthology of British Literature, 8th Ed. Vol. D. New York: Norton. p. 478.
- Paul; Adams, Michael (2009). How English Works: A Linguistic Introduction (2nd ed.). New York: Pearson Longman. p. 152. ISBN 978-0-205-60550-7
- Algeo, John (2006). British or American English? A Handbook of Word and Grammar Patterns. Cambridge Univ. Press.
- Burchfield, R. W., ed. (1996). Fowler's Modern English Usage (3rd ed.).
- Dryer, Matthew S. (2005). "Order of adverbial subordinator and clause". In Haspelmath, Martin; Dryer, Matthew S.; Gil, David; Comrie, Bernard. The World Atlas of Language Structures. Oxford University Press. ISBN 0-199-25591-1.