That's a very good question! The number of lights on a Christmas tree can vary depending on personal preference and the size of the tree. A general rule of thumb is to use about 100 lights per foot of the tree, but this can be adjusted up or down depending on how bright or dim you want the tree to be. Some people prefer to use a few strands of lights to create a more subtle and elegant look, while others may use hundreds of lights to create a more vibrant and festive atmosphere. Ultimately, the number of lights you use is entirely up to you and your personal taste!