I once taught alongside a professor who would give an A to any final exam that properly employed the semicolon. She gave very few A’s, so few, in fact, that I hesitate to bring up the secret use of the semicolon. People have enough trouble with the conventional use.

The Conventional Use of Semicolons

A semicolon is placed between two independent clauses in lieu of a period. (An independent clause is a set of words that could stand alone as its own sentence.) The semicolon indicates a close relationship between the two independent clauses, a relationship so close that a period would seem…a bit gauche.

I would not wear a mink scarf with the heads still on; that is simply not who I am.

Taking the heads off would not make it measurably better; the heads are only half the problem.

Note that in the cases above, a period would also…