Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. In mathematics, the universality of zeta-functions is the remarkable property of the Riemann zeta-function and other, similar, functions, such as the Dirichlet L-functions, to approximate arbitrary non-vanishing holomorphic functions arbitrarily well. The universality of the Riemann zeta function was first proven by Sergei Mikhailovitch Voronin in 1975 and is sometimes known as Voronin''s Universality Theorem. A mathematically precise statement of universality for the Riemann zeta-function (s) follows.