Melanoma is a type of skin cancer that develops from melanocytes, the cells responsible for producing the pigment melanin, which gives skin its color. It is considered the most dangerous form of skin cancer because it can spread (metastasize) to other parts of the body if not detected early. Melanoma often appears as a new mole or an unusual growth on the skin, or it may develop from an existing mole that changes in shape, color, or size. It is typically caused by excessive exposure to ultraviolet (UV) radiation from the sun or tanning beds. Early detection and treatment of melanoma are crucial, as it can be successfully treated if caught early. Key warning signs are often summarized by the "ABCDE" rule: - **A**symmetry - **B**order irregularity - **C**olor variation - **D**iameter (usually larger than 6 mm) - **E**volving (any changes in the mole over time).