Cannabidiol (CBD) is a phytocannabinoid discovered in 1940. It is one of 113 identified cannabinoids in cannabis plants, along with tetrahydrocannabinol (THC), and accounts for up to 40% of the plant's extract. As of 2022, clinical research on CBD included studies related to the treatment of anxiety, addiction, psychosis, movement disorders, and pain, but there is insufficient high-quality evidence that cannabidiol is effective for these conditions. CBD is also sold as a herbal dietary supplement promoted with unproven claims of particular therapeutic effects.