Comma

The comma , is a punctuation mark that appears in several variants in different languages. Some typefaces render it as a small line, slightly curved or straight, but inclined from the vertical, others give it the appearance of a miniature filled-in figure 9; placed on the baseline. In many typefaces it is the same shape as an apostrophe or single closing quotation mark ’.

The comma is used in many contexts and languages, mainly to separate parts of a sentence such as clauses, and items in lists mainly when there are three or more items listed. The word comma comes from the Greek κόμμα (kómma), which originally meant a cut-off piece, specifically in grammar, a short clause.^[1][2]

A comma-shaped mark is used as a diacritic in several writing systems and is considered distinct from the cedilla. In Byzantine and modern copies of Ancient Greek, the "rough" and "smooth breathings" (ἁ, ἀ) appear above the letter. In Latvian, Romanian, and Livonian, the comma diacritic appears below the letter, as in ș.

In spoken language, a common rule of thumb is that the function of a comma is generally performed by a pause.^[3]

In this article, ⟨x⟩ denotes a grapheme (writing) and /x/ denotes a phoneme (sound).