The word alchemy was borrowed from Old French alquemie, alkimie, taken from Medieval Latin alchymia, and which is in turn borrowed from Arabic al-kīmiyā’ ‘philosopher's stone’. The Arabic word is borrowed from Late Greek chēmeía, chēmía ‘black magic’ with the agglutination of the Arabic definite article al- . This ancient Greek word was derived from the early Greek name for Egypt, Chēmia, based on the Egyptian name for Egypt, kēme (hieroglyphic khmi, literally ‘black earth’, as opposed to red desert sand).

The Medieval Latin form was influenced by Greek chymeia meaning ‘mixture’ and referring to pharmaceutical chemistry.

Defining objectives of alchemy are varied but historically have typically included one or more of the following goals: the creation of the fabled philosopher's stone; the ability to transmute base metals into the noble metals (gold or silver); and development of an elixir of life, which would confer youth and longevity.

Though alchemy played a significant role in the development of early modern science, it differs significantly from modern science in its inclusion of Hermetic principles and practices related to mythology, magic, religion, and spirituality.

Alchemy covers several philosophical traditions spanning some four millennia and three continents. These traditions' general penchant for cryptic and symbolic language makes it hard to trace their mutual influences and "genetic" relationships. One can distinguish at least three major strands, which appear to be largely independent, at least in their earlier stages: Chinese alchemy, centred in China and its zone of cultural influence; Indian alchemy, centred around the Indian subcontinent; and Western alchemy, which occurred around the Mediterranean and whose centre has shifted over the millennia from Greco-Roman Egypt, to the Islamic world, and finally medieval Europe. Chinese alchemy was closely connected to Taoism and Indian alchemy with the Dharmic faiths, whereas Western alchemy developed its own philosophical system that was largely independent of, but influenced by, various Western religions. It is still an open question whether these three strands share a common origin, or to what extent they influenced each other.

The introduction of alchemy to Latin Europe occurred on 11th February 1144, with the completion of Robert of Chester's translation of the Arabic Book of the Composition of Alchemy.

Alchemists contributed distillation to Western Europe, so it wasn't all bad.

The attempts of alchemists to arrange information on substances, so as to clarify and anticipate the products of their chemical reactions, resulted in early conceptions of chemical elements and the first rudimentary periodic tables. They learned how to extract metals from ores, and how to compose many types of inorganic acids and bases.

During the 17th century, practical alchemy started to disappear in favour of its younger offshoot chemistry, as it was renamed by Robert Boyle, the "father of modern chemistry". In his book, "The Skeptical Chymist", Boyle attacked Paracelsus and the natural philosophy of Aristotle, which was taught at universities. However, Boyle's biographers, in their emphasis that he laid the foundations of modern chemistry, neglect how steadily he clung to the scholastic sciences and to alchemy, in theory, practice and doctrine. The decline of alchemy continued in the 18th century with the birth of modern chemistry, which provided a more precise and reliable framework within a new view of the universe based on rational materialism.

In the eyes of a variety of esoteric and Hermetic practitioners, the heart of alchemy is spiritual. Transmutation of lead into gold is presented as an analogy for personal transmutation, purification, and perfection. This approach is often termed 'spiritual', 'esoteric', or 'internal' alchemy.

Practitioners and patrons such as Melchior Cibinensis and Pope Innocent VIII existed within the ranks of the church, while Martin Luther applauded alchemy for its consistency with Christian teachings. Both the transmutation of common metals into gold and the universal panacea symbolized evolution from an imperfect, diseased, corruptible, and ephemeral state toward a perfect, healthy, incorruptible, and everlasting state, so the philosopher's stone then represented a mystic key that would make this evolution possible. Applied to the alchemist himself, the twin goal symbolized his evolution from ignorance to enlightenment, and the stone represented a hidden spiritual truth or power that would lead to that goal.