Punctuation Power: The Comma and The Em Dash

Sometimes in writing, we encounter phrases and thoughts that, though separate and different, ought to be a part of one greater sentence. While the period, the exclamation point, and the question mark are common forms of punctuation, those are only used to end a sentence rather than join them. In order to combine these phrases, we can use two very important tools: the comma (,) and the em dash (–). Though both forms of punctuation are used to divide a sentence and denote a pause or break in speech, there are notable differences and uses.

The comma can be used for several purposes: (1) to separate adjectives or items in a list, (2) when addressing a person, (3) to set off sentences that interrupt flow, and (4) to separate clauses.

To separate adjectives or items in a list:

The old, bedraggled man sighed.

I went to the store to buy apples, pears and potatoes.

When addressing a person:

Hello, Margot.

Marcus, have you seen my notebook?

To set off sentences that interrupt flow:

Some days, when the sun is shining really bright and the weather is warm, I sunbathe on the roof.

Robert usually buys lunch at the store around the corner, he likes the turkey sandwich, but today he just ate school lunch.

To separate clauses:

Because it was raining, the volleyball match was canceled.

Like the comma, the em dash also has multiple uses: (1) to separate a parenthetical thought or other interruption, and (2) to denote an unfinished sentence.

To separate a parenthetical thought:

Janie ordered another cup of coffee – not that she wasn’t already buzzing with energy – and took a seat close to the counter.

To denote an unfinished sentence:

“But I – ” he started. He was cut off by his mother’s yelling.

So now that you know the practical and most common uses for the comma and the em dash, don’t be afraid to use them – just remember not to overdo it!