A fiber optic Christmas tree is a type of artificial Christmas tree that uses lights to create a festive and colorful display. It's called a fiber optic tree because the lights are made of tiny strands of fiber-optic cable that transmit light to the tip of each branch, creating a shimmering, glowing effect. Fiber optic trees come in a variety of sizes and shapes, from small tabletop models to large floor-standing models. They are popular for their bright, colorful, and eye-catching displays, which can be easily customized with different lighting settings.