RSO is a type of oil taken from cannabis plants, usually a high concentrate of THC. Unlike other extraction processes that just extract the trichomes from buds, RSO is made from the entire plant and contains all of its cannabinoids, terpenes, and other compounds. Its production process is complicated and can take a while. It is usually very dark in color, very similar to tar or molasses, and because of the amount of plant matter in it, it does not have a great taste.