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Use commas only when breaks are needed for readability or to avoid confusion or misinterpretation.

APS style requires the use of the series comma.

When to Use a Comma

To separate elements (words, phrases, or clauses) of a simple series of more than two. If any of the elements contain internal punctuation, then separate them with semicolons.

To set off an introductory clause beginning with a subordinating conjunction (e.g., “if,” “although,” “because,” “when,” or “since”) or an introductory phrase (“To accomplish the task, we…”) or participial phrase (“Using hippocampal slices from adult rats, we…”). Beware the dangling participle! For example, you may see “After performing the experiments, the rats returned to their cages…” This is both 1) humorous (well, to copy editors) and 2) a mistake that authors make frequently and should be corrected.