December 21st was the Winter Solstice: the "shortest day" of the year. After that, the hours of sunlight start increasing.

You can find out more abut the winter solstice by checking out the FAQ of the U.S. Naval Observatory Astronomical Applications Department's Web site.  Or, to learn more about the diverse ways the winter solstice is celebrated, search "Winter Solstice" in Britannica Online from the IU Libraries' Find Information Web page.