Alchemy, originally derived from the Ancient Greek word khemia (Χημία) meaning "art of transmuting metals", later Arabized as al-kimia (الكيمياء), is both a philosophy and an ancient practice focused on the attempt to change base metals into gold, investigating the preparation of the "elixir of longevity", and achieving ultimate wisdom, involving the improvement of the alchemist as well as the making of several substances described as possessing unusual properties. The practical aspect of alchemy generated the basics of modern inorganic chemistry, namely concerning procedures, equipment and the identification and use of many current substances.

Alchemy has been practiced in Mesopotamia (comprising much of today's Iraq), Egypt, Persia (today's Iran), India, China, Japan, Korea and in Classical Greece and Rome, in the Post-Islamic Persia, and then in Europe up to the 20th century, in a complex network of schools and philosophical systems spanning at least 2500 years.