Absolute values and their completions - such as the p-adic number
fields - play an important role in number theory. Krull's generalization
of absolute values to valuations made applications in other branches of
mathematics, such as algebraic geometry, possible. In valuation theory,
the notion of a completion has to be replaced by that of
"Henselization". This book develops the theory of valuations as well as
of Henselizations, based on the knowledge acquired in a standard
graduate course in algebra.