Rules For When to Use a Semicolon

Misunderstood and Misused

The semicolon; is one of the most misunderstood and misused of punctuation marks. This is probably both because of its similarity to the colon : and its specialized uses. Quite frankly, most writers will not have a need for a semicolon on a regular basis in their writing. So they often forget when and where to use it.

In this lesson, we'll learn how to tell a semicolon from a colon, how to use a semicolon to join independent clauses (And if you don't know what an independent clause is, don't sweat it; we'll go over that too) and how to use a semicolon in a list.

Semicolons and Colons

So before we go any further, let's distinguish a semicolon from a colon. A semicolon is a period on top of a comma (;) and a colon is two periods on top of each other (:). It's easy to see why people get them confused: they look similar, have similar-sounding names, and even occupy the same key on a keyboard.

But that's pretty much where the resemblance stops. Grammatically, they do entirely different things. A colon is typically used to introduce a list that follows an independent clause, just like I used it in the last paragraph. (See what I did there?) But semicolons do something entirely different, which we'll get into now.

Joining Independent Clauses

A semicolon's main job is to join two independent clauses. Now, you're probably wondering, 'But what's an independent clause?' Well, calm down. Because an independent clause is just another way to say a complete sentence. Or more specifically, a group of words that could be a complete and grammatically correct sentence on it's own. So all of these are independent clauses:

• That math test was hard
• I'm really sad
• It is almost summer vacation
• I'm not paying attention in school

Now you could put a period after each of these clauses and make them their own sentence. That would be grammatically correct, but this can also get boring if your writing is just a bunch of very short sentences. So people often combine clauses into longer, more complex sentences. But if you try to join two independent clauses together with just a comma, you run into the dreaded comma splice:

I'm not paying attention in school, it is almost summer vacation.

So how do we join independent clauses together to make complex sentences without committing a comma splice and making our readers reach for their red pens? There are two ways. The first is to join the independent clauses with a comma and a coordinating conjunction such as and, but, for, or, nor, so, and yet. Fixing our earlier sentence with a coordinating conjunction might look like this:

I'm not paying attention in school, and it is almost summer vacation.

So now that's grammatically correct, but it sounds a little weird, doesn't it? None of the coordinating conjunctions do a great job joining those two thoughts together. But having them as two short sentences can be boring. What can we do?

Well, that's where our friend, the semicolon, comes in. His job is to allow you to join two independent clauses together without using a coordinating conjunction and without committing the sin of the comma splice:

I'm not paying attention in school; it is almost summer vacation.

So you're thinking, 'That's it? This punctuation mark I've been so afraid of and always seem to use wrong just does this one specific thing?' And my answer is 'Yeah, pretty much. It's super easy after you learn the rule.' With one exception we'll get to in a minute, semicolons exist simply to join two independent clauses.

Semicolons in Lists

Now let's get to that exception. While semicolons mainly exist to join independent clauses, a while ago, some smart writers figured out they could also be put to use to bring clarity to a specific, and fairly rare, writing situation.

We all know you're supposed to use commas in lists, such as:

I went the store and bought eggs, milk, and cheese.

The commas help separate the items in the list. But what if the items in your list are more than one word, and what if the items actually contain commas themselves, like this:

I have lived in Phoenix, Arizona, Las Vegas, Nevada, and Tampa, Florida.

That looks super confusing, right? 'Phoenix, Arizona' is one item in my list, but since it already includes a comma, it's hard to tell when the commas are separating city and state and when they are separating items in the list. But what if we did this?

I have lived in Phoenix, Arizona; Las Vegas, Nevada; and Tampa, Florida.

Semicolon to the rescue! The semicolons clearly distinguish between the items in the list and make it easier to read. So that is the only other time you would use a semicolon.