κόμμα

Aristophanes of Byzantium, head of the Library of Alexandria around 200 BCE, is credited with the first systematic punctuation. He divided sentences into three units of increasing length: the komma (κόμμα, a short clause), the kolon (a medium clause), and the periodos (a full sentence). Each was marked with a dot at a different height. The komma — from koptein, "to cut" — was the shortest cut, the smallest unit of meaning that could stand on its own.

For over a thousand years, Aristophanes' system was more theoretical than practical. Ancient and medieval manuscripts were written in scriptura continua — no spaces, no punctuation, words running together in an unbroken stream. Readers were expected to parse the text aloud, and their breath and intonation did the work that commas would later perform on the page.

Aldus Manutius the Elder, the Venetian printer-publisher, standardized the modern comma in the 1490s. He lowered Aristophanes' mid-height dot into a small curved mark at the baseline — a virgula, or "little rod." His grandson, Aldus Manutius the Younger, published a punctuation manual in 1566 that codified the comma's rules. The comma as we know it is a product of the printing press, not the quill.

The comma is now the most frequently used punctuation mark in English. Style guides devote more pages to the comma than to any other symbol, and the Oxford comma — whether to use a comma before "and" in a list — has generated lawsuits, divorces of opinion among editors, and at least one $5 million legal settlement in Maine in 2017 over the interpretation of a missing serial comma in overtime law.