I've heard that the Grinch is a character from a story about a Christmas Eve when the Grinch tried to steal Christmas by stealing all the presents from the children. He was unsuccessful because the children's love for Christmas was too strong. The Grinch was later inspired to join in the spirit of Christmas and give gifts to the children instead of taking them. The story is about the importance of generosity and kindness, and how the spirit of Christmas can bring people together.