Saturnalia originally fell on a single day, December 17, honoring the Roman god Saturn, but by the late Republic and into the Empire the festival had expanded into a full week, the seven day duration this rule records, through a combination of official extension and popular practice that outran the formal calendar. The festival was among the most widely attested and best loved of Roman public holidays, and Macrobius's later literary dialogue, itself titled Saturnalia and set as a conversation held during the festival, is a major source for how Romans of the later Empire understood its customs and history.
Its most distinctive features were forms of structured social reversal, with the ordinary hierarchy between masters and slaves loosened for the festival's duration, including slaves being served at table by their masters in a temporary and ritualized inversion of daily life, alongside general license, feasting and gambling permitted outside the ordinary rules governing Roman public conduct. Gift giving, particularly small wax candles called cerei and clay figurines called sigillaria, was a well attested custom of the festival, referenced by Roman poets including Martial, whose surviving epigrams include several written specifically as accompaniments to Saturnalia gifts.