Homeopathy is a system of medicine based on the principle that "like cures like," using highly diluted substances to stimulate the body's ability to heal itself. It was founded by Samuel Hahnemann in the late 18th century after he observed that substances given in large doses to induce symptoms in healthy individuals could cure people exhibiting similar symptoms. Homeopathy uses plant, animal, and mineral substances in extremely diluted doses to treat illnesses. While controversial, proponents believe homeopathy is a natural, safe, and effective approach that addresses the underlying cause of symptoms rather than just treating symptoms.