Semicolons are pesky things. When I taught Freshman Composition, I required students to use the semicolon in at least once in their first essay; they found it difficult because they had never mastered the rules for using it.

Are there rules? For high school and college students, there are conventions, but for writers, we punctuate for effect, clarity, emphasis, style or voice. We follow conventions when it works and break conventions–blithely, courageously, heroically–when we need to.

Still, there are uses and abuses of semicolons.

Uses of Semicolons

The first and foremost use of a semicolon is to connect two related thoughts.

I went to the store; I bought watermelon.

The semicolon forces the reader to make a pause, shorter than you would with a period, but longer than you would for a comma; however, the pause isn’t as abrupt as for a dash. The semicolon pause creates that relationship, close, but not too close, not too abrupt.

A colon is similar, but specifies a specific relationship. The first half gives a general statement, while the second amplifies that in some way.

The dress was awful: wrong color, baggy fit and too long.
The dress was awful: my sister could have worn it, but it was too big for me.

Back to the semicolon, the very pause itself is a reason to use a semicolon. Arthur Plotnik, in Spunk and Bite, says, “With a semicolon, there is a split-second of tease. . Semicolons inject expectation into sentences, and in literature expectancy is a good thing; it creates subliminal tension followed by release: the quiet ‘ah’ of art.” (p. 174)

If you take the sentence, “Nice haircut,” the delivery of that sentence can drastically change the meaning. You can read it with sarcasm, with enthusiasm, with scorn, with delight. Mark Twain once said that the way a person reads your work should not be up to them; on the page should be enough information that they MUST read it the way you intended.

One of the tools we have to accomplish that is punctuation, which forces readers to pause here and there for varying lengths of time and thus create implied relationships. The semicolon is useful when you have two related ideas which have equal weight, one isn’t subordinate to the other. Further, for some reason, you don’t want to use a coordinating conjunction to connect the thoughts. (In rhetoric, this is called parataxis; hypotaxis concerns ideas where one is subordinated to another demanding a different punctuation.)

Semicolon Errors

Both sides of the semicolon must be complete sentences. Remember the definition of a complete sentence: a subject-verb combination that makes a complete statement. What precedes and what follows the semicolon must be capable of standing alone.

These are fragments:
The reason for the loss in yardage being
the broken shoe-string on the left guard’s shoe.

These are common semicolon errors because these are not complete sentences:
For example; . . . .
Because the snow was deep and the temperature below zero; . . . .
The work having been finished by five o’clock; . . .

When to use semicolons

Use semicolons when you need to combine ideas into a single, more powerful sentence that conveys the information you’ve previously expressed in two or three or four sentences. During revision you should look for paragraphs with too many short sentences with parallel ideas.

   Caesar, try on this toga; it seems to be your size.
   E.T, don’t phone home; it’s too expensive.
   Singapore has 11,910 people per square mile; Mongolia has only three.
   Be content with your lot; one cannot be first in everything.
   It’s not going to be one big party; it’s not going to be fireworks and cakes.
   Forget defensive driving; practice paranoid driving.

Use of conjunctive adverbs (connectors) such as however, hence, therefore, thus, then, moreover, nevertheless, likewise, consequently, accordingly. The use of a comma after the connector is optional.
Subject Verb; however, Subject Verb.

This gadget won’t work; therefore there is no sense in buying it.

Use a coordinating conjunction (also a connector) such as and, or, for, but, nor, yet, or so.

Subject Verb; Subject Verb, and Subject Verb.

Subject Verb, but Subject Verb; Subject Verb

It was snowing outside, and in the building Harold felt safe; he dreaded leaving his shelter for the long dangerous trip home.
It was radical; it was daring, but mostly it was cheap.

Connect more than two independent clauses.

Subject Verb; Subject Verb; Subject Verb.

North bid one club; East passed; South bid one spade; West doubled.
Touch not; taste not; handle not.

Plotnik also suggests that semicolons can be used to effect, for example, when a lawyer pauses dramatically after each item in a list of his client’s afflictions. Each pause, Plotnik says, creates a “sympathy” pause.

“[He suffered]. . . headaches; vertigo; nausea; hypertension; scalp tenderness; insomnia; mood dysphoria; photosensitivity; and phonophobia.) ( — John Cassidy, “The Misery Broker,” The New Yorker)

So, while the Punctuation Police may say that there are strictly regulated uses for semicolons, don’t hesitate to use them for effect. The main reason to learn punctuation is to have control over your language, so be able to say what you mean; and, it’s important to put what you mean onto the page, so the reader has no choice, but to read it your way.