Homeopathy is a system of medicine that was developed in the late 18th century by Samuel Hahnemann. It is based on the principle of "like cures like," which means that a substance that causes symptoms in a healthy person can be used to treat similar symptoms in a sick person. Homeopathic treatments involve highly diluted substances, often in the form of tinctures or sugar pellets, that are believed to stimulate the body's vital force and promote self-healing.