Among popular complementary therapies are acupuncture, osteopathy, chiropractic, homeopathy and herbal medicine.
Other therapies include aromatherapy and massage.
Some therapies are part of complete medical systems from other cultures, such as traditional Chinese medicine, Tibetan medicine and Ayurvedic medicine from India.
Surveys have suggested that around one in three people in the UK has tried at least one form of complementary therapy, and that one in ten GPs is actively involved in complementary medicine.
Complementary medicine is used in the treatment and prevention of a wide range of ailments, as well as for pain management and general health promotion. Some people use it for chronic ailments such as arthritis and migraine.