Hashish, often known as hash or hashish oil (BHO), is a cannabis product composed of compressed or purified preparations of stalked resin glands, called trichomes. It contains the same active ingredients—such as THC and other cannabinoids—but often in higher concentrations than unsifted buds or leaves. It is consumed by being heated in a pipe, hookah, bong, bubbler, vaporizer, hot knife (placed between the tips of two heated knife blades), smoked in joints, mixed with cannabis buds or tobacco, cooked in foods or smoked as bottle tokes ("brewing bots").