Cornrows are a type of braid that have been in existence for hundreds of years. They became wildly popular in modern times when Bo Derek wore cornrows in the popular movie "10" co-starring Dudley Moore. Cornrows are created when a row of hair is sectioned off and braided, usually straight or at an angle. Depending on the lenght and thickness of hair, it can take anywhere from a few to many hours to create cornrows on the entire head.