Punctuation Best Practices for Lists: When to Use Colons and Em Dashes

When it comes to punctuation in written communication, especially in information-dense documents, the choice of symbols can significantly impact readability and clarity. This article discusses the appropriate use of colons and em dashes, as well as some examples of best practices in punctuating lists.

An Overview of Colons and Em Dashes

Colons and em dashes are punctuation marks that serve specific functions in sentences and lists. A colon is used to introduce a list, a summing-up, or an explanation that follows a statement. Em dashes, on the other hand, are used for emphasis or to provide an interruption in a sentence. They can create a stronger break in the flow of a sentence than a comma or a dash.

When to Use a Colon

Colons are particularly useful when you need to introduce a list. For example, if you are writing a sentence that will be followed by a list of items, a colon is the appropriate choice. Consider the following example:

The list is as follows:

Coffee Tea Milk

Here, a colon clearly indicates that what follows is a list of items.

Another common scenario where a colon is used effectively is when introducing a summary or explanation that follows a statement. For instance:

The benefits of regular exercise are clear: reduced stress, improved health, and increased energy.

Here, the colon is used to introduce the explanation of the benefits of regular exercise.

When to Use Em Dashes

Em dashes are used to create a strong break in the flow of a sentence and to emphasize something within the sentence. They can also be used for stylistic reasons to add a sense of drama, surprise, or sudden interruption. For example:

The em dashes make it easier to read when you're in a situation like this: a long list of items separated by commas.

Alternatively, in the following example, the em dash is used for dramatic effect:

She couldn't believe it—something she had long feared had come true.

Best Practices for Lists

In the realm of information-dense documents, the use of colons before lists can help a reader's eye re-locate quickly to the list if needed. However, the use of a colon to introduce a list is optional and can be alternated with other methods like em dashes or bulleted lists, depending on the clarity and style of the document.

For instance, if you have a long list of items separated by commas, a colon might not be as effective. In this case, em dashes can be a better option, as they create a strong break that is easier to read:

No colon. OK as written but if I were editing this for a client I would use em dashes up front.

Even a better solution: use a bulleted list where you would use a colon, especially since it appears there are several more items than we see. In this situation, a bulleted list is my FIRST CHOICE.

Example:

Coffee Tea Milk Water Juice

Contracts and Punctuation

In the context of contracts and formal documents, punctuation can have a different meaning. Punctuation in contracts is often interpreted to have nuanced relevance that doesn't exist in ordinary writing. Therefore, when working inside a contract or in a document that could be referenced by a contract, you should ensure your punctuation conforms to the legal intent of the document. For instance:

Chapter 1: Introduction

Section 1: Terms and Conditions

Items are listed in the following manner, and the punctuation used in the contract reflects the legal precision required:

Item A Item B Item C

As a general rule, if the context is the ordinary world, it is usually fine to use colons to introduce lists, but a colon is not wrong. Formatting also plays a significant role in this decision. If you intend to format your list items with bullets, I prefer a colon as the mark to introduce the list.

For example:

Vegetable A Vegetable B Vegetable C

In conclusion, the choice between colons, em dashes, and bulleted lists depends on the context and the clarity you want to achieve. By understanding the role of each punctuation mark, you can enhance the readability and effectiveness of your written documents.