Janus is the ancient Roman god who gives January its name and is symbolized by looking both backward and forward.
Roman tradition associated Janus with beginnings, transitions, doorways, gates, and passages. He was often depicted with two faces, one facing the past and one facing the future. That symbolism made him especially appropriate for the beginning of a new year, when people reflect on the year ending and anticipate the year ahead.
January is named from the Latin Ianuarius, meaning the month of Janus. In the Roman calendar, January eventually became the first month of the year, although calendar systems and starting dates changed over Roman history. The Julian calendar reform under Julius Caesar helped establish January 1 as the beginning of the civil year.
Janus is sometimes incorrectly described as a Greek god. He is a distinctly Roman deity without a direct Greek equivalent. His two faces also do not mean he was a god of deceit; they primarily represent thresholds and time's opposing directions.