Out of more than 30,000 runs in the three sliding sports — bobsled, luge and skeleton — Whistler has seen 340 crashes.

— David Epstein, “Luge dangers exaggerated,”

CNN Opinion, February 16, 2010

“Skeleton” in the sentence above refers to a winter sport (AKA tobogganing). The writer uses only one comma because it’s standard journalistic practice to leave out a comma before “and” in a list of three or more items in a series.

For most writers, though, we’d strongly recommend adding a comma after “luge” in this sentence. Always including the series comma means your reader will always understand how many separate things you’re listing in a sentence.

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For more guidelines on how to use commas correctly and confidently, see our updated book Professional Writing Skills: A Write It Well Guide, which will ship on March 5th!