Conjunctions are words which join phrases, clauses and sentences.

Conjunctions have three basic forms which are shown in the table below.

Form Words Sentences
Single Word and, but, because, although, or, etc. Do you want chips or cake.
Compound provided that, as long as, in order that/to, etc. You need to exercise in order to lose weight.
Correlative both/and, either/or, neither/nor, not/but, not only/but also Either Monday or Tuesday is fine.

Not only should you eat fruit, but also vegetables.

Conjunctions also have two functions, as shown below.

Type Function Position Example Sentences
Coordinating conjunctions Join equal (independent) parts of a sentence. Always come between the words/clauses that they join. Jack and Jill went up the hill.

The water was warm, but I didn't go swimming.

Subordinating conjunctions Join subordinate clauses to main clauses. Usually come at the beginning of subordinate clauses. I went swimming although it was cold.

Although some people say it's not correct to use conjunctions at the beginning of a sentences, many famous writers do so.

Conjunction for Kids. Kiddle Encyclopedia.