Colons and semicolons have very basic assumed functions like joining related sentences, or introducing lists. But the rules and other uses are more intricate than we assume. Without any clear-cut basic lines, most of us are left trying to guess if placing a colon in our sentence is worth the risk. Using updated guidelines from the Chicago Manual of Style, the Associated Press Style Guide (AP), and a number of handwritten examples provided here, you’ll know exactly where colons and semicolons belong in your writing.

Colons

The general operation of a colon varies depending on the circumstances. But it is primarily used for emphasis, along with the introduction of lists or other elements like questions or quotes. Due to the function to emphasize, be sure not to overuse them and lose your reader.

Emphasis

Starting out with the basics, there is a way that colons can be used for nothing more than emphasis. The function in this sentence highlights the fact there is only one remaining option left for these people to follow. While it is easy to think that colons emphasize what follows it, that impact lands on the previous clause. 

Lists

When it comes to lists, both style guides agree on colon placement in relation to sentence structure. The colon belongs after the last word of any introductory word or phrase used. In terms of types of lists, what you see here is the commonly used run-in list. A run-in list is used as part of the overall sentence. Due to the nature of the run-in structure, a colon helps to keep the list there without sacrificing clarity.

Introductory phrases

While it would be easy to assume all run-in lists are treated the same, the introductory phrase makes a big difference. By plugging in the phrase as follows, the colon becomes required by both style guide standards. Now, this doesn’t apply to all introductory phrases, but the more formal type that are similar to what was used here.

Common colon assumptions

Now, before we move on to other rules, there is one important assumption to break before it becomes a habit. Chicago points out that colons don’t have a place with every single list. When a list serves as the object of a verb, then the colon might seem right, but it is actually out of place. Look at the sentence for this instance, the list of projects is the object of the verb covered. Therefore, the list needs to be introduced by a comma. 

The one exception

However, as it is with a number of guideline rules, there is an exception here. When a word or phrase introduces a list with the absence of a verb, or is crafted so the verb is understood, then the colon is required. In terms of this case, there is no clearly stated verb, but it’s understood that there are rules on what can come into a certain space. With that in mind, you can see that the colon is required here.

Semicolons

Much like colons, semicolons fit best between two independent clauses in the absence of any conjunction. However, the semicolon really only has one solid function, to link two independent clauses and show the close relationship of their context or elements. Besides sentence construction, semicolons are placed for the sake of clarity.

Complex series

Switching over to the semicolon standards, there are a lot of questions on what to do with big complex series, so let’s break it down. Usually in these cases, the elements have their own internal punctuation that isn’t flexible. Instead of a flood of commas that could have a number of different purposes, semicolons separate each group. For the current example, you’re trying to keep the initial with the name along with the job title of that person who was involved. Each person is kept with the right job and set off by semicolons to clearly establish who was on this team and what they did. 

A link with conjunctions

Similar to the use of the colon, a semicolon can separate independent clauses and work as a link at the same time. It denotes the close relationship between both sentences. Doing so in AP Style, a conjunction is called for, following the linking semicolon. Take a look at the given message, both sentences fit as independent clauses. Given that circumstance, they could each be their own sentence if you wanted to go that direction. But if you want to use the semicolon, then the conjunction is required with the semicolon preceding.

A link without conjunctions

Now, if you’re dealing with Chicago style, it’s a bit of a different story. They suggest that the conjunction be taken out if you are using the semicolon as a link. When that is the case, it’s even more important that you make sure your sentences are clear independent clauses, so the lack of any conjunction doesn’t lead to reader confusion. The current example is a good visual to understand what that might look like in your own writing. But again, you always have the option to make your life easy and use a period instead.

Conjunctive and transitional adverbs

Certain adverbs act as transitions, and at the same time coordinating conjunctions, when joining two independent clauses. They are commonly called transitional or conjunctive adverbs. Due to their nature, more often than not, you’d see these words set off by commas in a sentence. Chicago explains that these adverbs should be preceded by a semicolon and then followed by a comma if needed. Let’s break it down with the visual a little more. However is the transitional adverb here which is why the semicolon stands in front of it and the comma still follows. When dealing with that type of adverb, this is what the sentence structure would look like by Chicago standards.

“Then” as a transitional adverb

Among other adverbs with special rules is the use of then between independent clauses. Chicago points out that then is actually a shortened version of and then. Normally, this particular adverb only takes a comma when used. However, when the and is physically absent, the semicolon is a possible option, like you see in the example. When the and is present, the comma is your only choice. Nevertheless, when it is only the use of then neither direction is discouraged. 

“That is” expressions

That is expressions are a very specific type of introductory phrase, clearly trying to draw attention to any statement that follows. When you see these phrases in texts they are commonly followed by a comma, which can be considered a perfectly fine placement. However, because these statements specifically work to express deeper detail, they should be preceded by a semicolon as well. Chicago standards call for this to happen since it technically shows a close relation between the first statement and the explanation that follows. In the example, that’s exactly what happens, the semicolon helps to keep the context connected through both independent clauses. 

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