Among its four uses, the structure comma identifies elements that communicate an emphatic contrast from the rest of the sentence.

Use the Comma with Contrasting Phrases and Clauses

When a phrase or clause expresses a strong contrast from the rest of its sentence, separate it with a comma.

The communicated antithesis might be a contrast of coordinate elements:

The box contained old photographs,↑not old letters.

Similarly, a dependent clause might also express an emphatic contrast:

We won the match,↑although we played our worst so far this season.

Usually, a dependent clause does not receive a structure comma when it follows the independent clause in a complex sentence. Notice in the example above, however, that antithetical dependent clauses do use the comma.

Use the Comma with In-Sentence Revisions

Another type of antithesis drastically revises a previous part of the same sentence. Instead of contrasting with a previous communication in the sentence, this technique replaces or significantly alters that previous communication:

We won the match,↑in our dreams, anyway.

The fans excoriated the setter for three mis-hits,↑or would have if the team hadn’t quickly escaped.

An em-dash is sometimes used instead of a comma to emphasize the antithesis even more: We won the match—in our dreams, anyway.

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