Today is Yule, or Yuletide, originally a Germanic festival connected to the god Odin and also the Anglo-Saxon festival Modraniht. Some of the festival's aspects, notably the Yule log, entered into Christian observance of Christmastide, and the word "yule" has entered into other languages (e.g., Jul in Norway, Denmark, and Sweden) in connection to the holiday.
In modern Neopaganism and in Wicca, the festival centers on the winter solstice. This site, for instance, gives several aspects of the Wiccan observance. This site is also informative.