FUNCTION

A comma separates parts of a sentence to mark a short pause or following ideas. If not overused, it helps improve the reading experience. It is also used in numbers to visually separate figures of larger categories. In the United States and most other English-speaking countries, in numerals of one thousand or more, a comma is used in between groups of three digits counting from the right (where a period is used for the same purpose in other European languages).

HISTORY

In Europe, the origins of many punctuation symbols, including the comma, come from the inventions of Greek scholar Aristophanes of Byzantium (3rd century BC) who created a set of symbols to help reading texts aloud.

DESIGN

The comma is basically a period with a tail. It has to be designed with enough differences to the period so that both can’t be confused with one another, even in smaller text sizes.

TYPOGRAPHIC RULES

A comma has no space before and is always followed by a space (U+0020) when used in a sentence. In numbers with decimals, it is used as such:

(European languages) 15.000,05

(English) 15,000.05