The semicolon indicates a longer pause than the comma. As with the comma, there are very specific rules governing when to use a semicolon. But learning where to use the semicolon is much easier. You only need to learn two rules.
A. Use the semicolon to connect two independent clauses not connected by a conjunction.
We learned earlier in this essay (Part 1, Section A) what an independent clause was, and we learned that two independent clauses can be connected by a comma followed by a coordinating conjunction. For example,
The room fell into blackness, and someone screamed.
If you didn't read that section, go back and read it now. Instead of using a conjunction to connect these two independent clauses, we could instead use a semicolon.
The room fell into blackness; someone screamed.
Our other option would be to simply make these two independent clauses into two separate sentences. We know that they can each stand on their own; that is what makes them independent clauses.
The room fell into blackness. Someone screamed.
Note that it is not an option to connect the two clauses simply with a comma and no conjunction.
The room fell into blackness, someone screamed.
This is a run-on sentence.
So how do you know whether you want to link two independent clauses with a conjunction, connect them with a semicolon, or separate them into two sentences? The answer is that you will usually use either the first or third option (as you probably have been). Only when the two clauses are closely related in meaning is a semicolon really appropriate.
All change is not growth; all movement is not forward.
Clint Eastwood's performance in A Fistful of Dollars is an early example of the antihero; Mel Gibson's performance in The Road Warrior is a more recent example.
Laurie was always reading; John never picked up a book.
Note that the only way two independent clauses can be linked with a comma is if you use a coordinating conjunction (these were explained earlier in this essay, in Part 1, Section A). Conjunctive adverbs are not conjunctions. Conjunctive adverbs indicate a close relationship in meaning between two independent clauses. They include hence, however, therefore, nevertheless, moreover, also, meanwhile, similarly, thus, instead, and others. These are not conjunctions, and so if you want to connect two independent clauses using one of these words, you must use a semicolon, not a comma. For example,
The president had not arrived; moreover, the vice president was also late.
They were denied admission to the event; therefore, they protested outside.
He hated the class; he expected, however, to get an A.
Note that any of the above examples could be split into two sentences instead.
B. Use the semicolon to separate a series of items which themselves contain commas.
As we learned earlier in this essay, in Part 1, Section C, items in a series are usually separated by commas. For example,
Her favorite TV shows were Seinfeld, Another World, and Friends.
But what if one or more of the items contains a comma?
The trial involved O.J. Simpson, the defendant, Nicole Brown Simpson and Ron Goldman, the victims, and Lance Ito, the judge.
The three items in our series are O.J. Simpson, the defendant, Nicole Brown Simpson and Ron Goldman, the victims, and Lance Ito, the judge. Using just commas, the series becomes very confusing. Separating each item instead with a semicolon makes the sentence much clearer.
The trial involved O.J. Simpson, the defendant; Nicole Brown Simpson and Ron Goldman, the victims; and Lance Ito, the judge.
Even if just one item in the series contains a comma, all items will be separated by semicolons.
As a student at Saint Anselm College, you can expect to work long, demanding days; meet good people; and form lasting memories.
Exercises for Part 2
Here are some exercises covering what you've just learned on the semicolon. Insert semicolons and commas where necessary.
- The death penalty is murder the society that supports it is made up of murderers.
- Cats are good dogs are evil.
- He owned a bright six-foot-long green iguana a dog and a cat.
- Anne was into pottery however her twin sister Jane hated it.
- Jeanne went to the store so John didn't have to.
- English class was exciting yet its early hour made many students skip.
- The college was a prison my dorm room was a prison cell.