The colors red and green have been associated with Christmas for centuries. Red represents the blood of Christ, while green symbolizes life and hope. These colors were first used to decorate the first Christmas tree in the 16th century. In the 19th century, green became the dominant color of Christmas, and red was added as a secondary color. Over time, the use of red and green together became the standard color scheme for Christmas decorations, and they have remained so to this day.