Prince Louis, the youngest child of the Prince and Princess of Wales, is celebrating his 6th birthday today. The young prince will be spending the day at school, but will celebrate when he returns home to Adelaide Cottage. His mother, Kate Middleton, is expected to make him a cake, and he may also have a chocolate beetroot cake, which is one of his favorite foods. Louis is fourth in line to the throne and is known for his enthusiastic personality and sweet moments.