Kief refers to the resinous trichomes of cannabis that may accumulate in containers or be sifted from loose, dry cannabis flower with a mesh screen or sieve. Kief contains a much higher concentration of psychoactive cannabinoids, such as THC, than that of the cannabis flowers from which it is derived. Traditionally, kief has been pressed into cakes of hashish for convenience in storage, but can be vaporized or smoked in either form.