The month of January is presumed to be named after Janus, a Roman god of two faces who symbolized beginnings and transitions. In mythology, one of Janus' faces looked ahead to the future and one behind to the past, just as January is a transitional period into a new year.
The month of January didn't even exist until approximately 700 B.C., when King Numa Pompilius added January and February to the calendar in order to create a calendar with a full lunar year. Previously, the Roman calendar was only 10 months long, winter had been regarded as period of no months, and March was the first month of the year. The month underwent further change when Julius Caesar added a 31st day to January in 46 B.C., as it was now the first month and began each new year.
Although January is usually regarded as a particularly cold and snowy month in the Northern Hemisphere, it is considered to be one of the Southern Hemisphere's warmest months. The gemstone representing January births is the garnet, a red silicate. January is the domain of two separate zodiac signs, Capricorn and Aquarius, with Capricorn representing the first half of the month and Aquarius covering the 20th onward.