Polypropylene, formerly known as olefin, is a solution-dyed synthetic material that is water- and stain-resistant, making it a popular option for indoor/outdoor carpeting. Since it is solution-dyed, it won’t fade, making it suitable for rooms that receive a lot of light or traffic from the outside or from a chlorinated pool. It functions better in low-pile carpets like Berbers since it is less robust than nylon (low, loop-pile carpeting with flecks of different colors).