Scholia (sg.: scholium or scholion, from Ancient Greek: σχόλιον, "comment", "interpretation") are grammatical, critical, or explanatory comments – original or copied from prior commentaries – which are inserted in the margin of the manuscript of ancient authors, as glosses. One who writes scholia is a scholiast. The earliest attested use of the word dates to the 1st century BC. Source: Wikipedia (en)