Commas vs semicolons vs em dashes: A magical mystery tour

Ah, punctuation. It breaks up our sentences with visual markers, structures our syntax, sets the pace for the reading experience, and so much more. But which punctuation should we use when there are so many options? Take these three sentences:

The results were in, and the voters were stunned.

The results were in; the voters were stunned.

The results were in—and the voters were stunned.

Can you spot the difference? While the first two simply report, the last one shows a change in mood or atmosphere. They are more or less the same length and offer the same information, but the tone is different. If the differences between commas, semicolons, and dashes are confusing—have no fear. Read on for a detailed breakdown with the help of the Fab Four.

Commas: Separate and join phrases within a sentence

Commas are probably the most versatile piece of punctuation. They can separate clauses, string together multiple elements, determine order and logic, and add information without overloading the sentence.

Connect two or more clauses with a conjunction (for example: and, but, so): Pete was out, and the fans were furious with Ringo.

Set off elements in a list: The Beatles consist of John, Paul, George, and Ringo.

Connect multiple adjectives: Sarcastic, irreverent John was always known as a troublemaker.

The comma can serve the above functions because it implies an “and.” This is why, in some writing styles, the serial comma (or “Oxford comma”) is not used, as it is seen as redundant—but we’re big fans of it.

Separate nonessential information from the main syntax: “Nonessential” here doesn’t mean unimportant; it means that the sentence is still grammatically correct with or without that phrase. For that reason, the placement of the commas determines the point of the sentence:

Brian, who is sometimes referred to as the Fifth Beatle, was their manager.

Brian, their manager, is sometimes referred to as the Fifth Beatle.

But now let’s use it all together:

The Beatles consist of John, Paul, George, and Ringo, though some also consider Brian, their manager, George, their studio recorder, or Stuart, their original bassist, to be the so-called Fifth Beatle.

Harder to read, right?

Because commas literally break up a sentence, they signal a mental pause. And when there are multiple pauses, it can take longer to digest a single sentence. That’s where semicolons and dashes come in.

Semicolons: Connect multiple sentences and lists, show relation

The semicolons might be the most intuitively designed piece of punctuation, a period on top of a comma indicates its exact function. Think of it as the comma’s big brother; when the poor little guy is all tuckered out, the semi steps in to do the heavy lifting.

Maintain an implied connection: Take the sentence above (or this one); it has two distinct thoughts, but they are closely related and complement each other:

The Beatles consist of John, Paul, George, and Ringo; some also consider Brian, their manager, George, their studio recorder, or Stuart, their original bassist, to be the so-called Fifth Beatle.

Unlike commas, semicolons do not take a conjunction when connecting two sentences; in those cases, they are the conjunction.

Structure a long or complex list:

In addition to the band’s discography, The Beatles also starred in films: A Hard Day’s Night, their debut film, a fictionalized glimpse into their lives on tour; Help!, an adventure to protect Ringo from a cult; and Lord of the Rings, a would-be psychedelic collaboration with director Stanley Kubrick that, sadly, never materialized.

Yeesh, can you imagine this list with just commas?

Em dashes: Set off a phrase, add dramatic effect

If commas are the busy workers trying to create order and semicolons are the strong shoulders to carry the big pieces, then em dashes—named as such because they are the width of a capital M—are the emotional cousins with a flair for the dramatic.

Separate nonessential information from the main syntax: In simplest terms, dashes can serve the same function as a colon, parentheses, or comma (that’s not part of a series). This creates a visual cue that there is information within the sentence that, while not essential for the syntax, is important context for the reader:

The musicians we know as The Beatles—John, Paul, George, and Ringo—first achieved fame in Hamburg, Germany.

Indicate importance: Where dashes really shine is the drama, the unexpected. Setting off a phrase with an em dash, often at the end of a sentence, indicates a tension in the tone and signals to the reader that this is the part to look at.

Much to their fans’ dismay, the Beatles announced their new lineup of John, Paul, George—and Ringo. *cue audience gasp*

Note: British English and some writing styles use a spaced en dash (for example, “Lucy, look – diamonds!”) for the same purpose.

 All together, now!

George Harrison, the youngest member, wrote some of the band’s greatest hits (such as “Here Comes the Sun” and “While My Guitar Gently Weeps”); he also—if you can believe it—financed the production of Monty Python’s Life of Brian.


The various forms of punctuation and their rules can be difficult to wade through. But once you know the differences between the available options, you can use the variety to not only relay information but also create interest, maintain your audience’s attention, and express your unique voice—all while increasing readability.

1 Comment

  • Dana DesJardins says:

    This is a quick and non-wonky explanation of how punctuation affects tone.

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