Industrial Hemp is a number of varieties of Cannabis sativa L. that are intended for agricultural and industrial purposes. They are grown for their seed and fiber content as well as the resulting byproducts such as oil, seed cake, hurds, etc. Industrial Hemp is characterized by being low in THC (delta-9 tetrahydrocannabinol) and high in CBD (cannabidiol). THC is less than 1% and in Canada and Europe the current legal level for cultivation is 0.3%. The ratio of CBD to THC is greater than one.
Currently it is illegal to grow hemp in the United States without a special Drug Enforcement Administration (DEA) permit being issued. The joke is that you can't get a permit.