Hogswatch Night is the festival celebrating the winter solstice and the New Year across much of the Disc. It falls on the 36th of December, the new year then beginning on the 1st of Ick..
Children looked forward to many things including, of course, a visit by the The Hogfather who visited during the night and brought presents.
Many Roundworld traditions have their counterpart on Discworld: carol singing, presents, warm alcoholic drinks, giant department stores with grottoes
Another Hogswatch tradition is that Witches must not go out that night. Like other rules, this one is observed at the discretion of the Witch.
The festival features most prominently in Hogfather
The Hogfather himself is a sort of scary version of Santa Claus with added tusks who wears red and white to signify blood on snow. He drives a sled drawn by wild boars rather than reindeer. He is the recent version of an ancient winter god associated with pig-killing and prehistoric pagan kingmaking rituals