Hemp is the common name for plants of the genus Cannabis, although the term is often used to refer only to Cannabis strains cultivated for industrial (non-drug) use. Licenses for hemp cultivation are issued in the European Union and Canada. In the United Kingdom, these licenses are issued by the Home Office under the Misuse of Drugs Act 1971. When grown for non-drug purposes hemp is often called industrial hemp, and a common product is fiber for use in a wide variety of products. Feral hemp or ditch weed is usually a naturalized fiber or oilseed strain of Cannabis that have escaped from cultivation and are self-seeding. 

Hemp seeds contains delta-9-tetrahydrocannabinol (THC), which is the psychoactive ingredient found in hashish and marijuana. The THC levels in hemp are minute and have very little intoxicating effects. THC is present in all Cannabis plant varieties to some extent. In varieties grown for use as a drug, where males are removed in order to prevent fertilization, THC levels can reach as high as 20-30% in the unfertilized females which are given ample room to flower.