What are Commas - There's More Grammar in Action on the Learning Videos Channel

Learn about commas and how they are used in grammar. A comma is a punctuation mark that you can use when you write dates, addresses and letters. You'll also learn how to use commas to separate adjectives, verbs and nouns in a sentence.

The comma ( , ) is a punctuation mark that appears in several variants in different languages. It has the same shape as an apostrophe ( ' ) or single closing quotation mark in many typefaces, but it differs from them in being placed on the baseline of the text.

Punctuation is much more recent than the alphabet. In the 3rd century BC, Aristophanes of Byzantium invented a system of single dots (distinctiones) that separated verses (colometry) and indicated the amount of breath needed to complete each fragment of the text when reading aloud.[3] The different lengths were signified by a dot at the bottom, middle, or top of the line. For a short passage (a komma), a media distinctio dot was placed mid-level ( · ). This is the origin of the concept of a comma, although the name came to be used for the mark itself instead of the clause it separated.

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

In general, the comma shows that the words immediately before the comma are less closely or exclusively linked grammatically to those immediately after the comma than they might be otherwise. The comma performs a number of functions in English writing. It is used in generally similar ways in other languages, particularly European ones, although the rules on comma usage – and their rigidity – vary from language to language.

The serial comma
Commas are placed between items in lists, as in They own a cat, a dog, two rabbits, and seven mice.

Whether the final conjunction, most frequently and, should be preceded by a comma, called the serial comma, is one of the most disputed linguistic or stylistic questions in English.

They served apples, peaches, and bananas. (serial comma used)
We cleaned up cores, pits and skins. (serial comma omitted)