The reason why Christmas trees are decorated is because it is a way to celebrate the holiday season and create a festive atmosphere. Decorating the tree adds a sense of magic and beauty to the room, and it is a way to express your creativity and personal style. The tradition of decorating Christmas trees dates back to the Middle Ages, when people would bring evergreen boughs into their homes to celebrate the winter solstice. Today, Christmas trees are decorated with a variety of ornaments, lights, and other decorations to create a beautiful and unique display that reflects the spirit of the season.