conjunction (language)

Coordinating conjunctions link parts of equal grammatical value; and, but, and or are the most common.

Subordinating conjunctions link subordinate clauses to the main clause in a sentence; among the most common are if, when, and though.

It is not considered good style to use too many conjunctions (particularly the same one repeatedly) in a sentence. Punctuation, especially commas (,) and semi-colons (;) can also connect clauses. A semi-colon is used to join sentences with closely related subjects, as in ‘John is sitting; his sister is standing.’ Writers commonly use a comma here, which is incorrect.