This book presents a self-contained introduction to H.M. Stark’s remarkable conjectures about the leading term of the Taylor expansion of Artin’s L-functions at s=0. These conjectures can be viewed as a vast generalization of Dirichlet’s class number formula and Kronecker’s limit formula. They provide an unexpected contribution to Hilbert’s 12th problem on the generalization of class fields by the values of transcendental functions.This volume also treats these topics: a proof of the main conjecture for rational characters, and Chinburg’s invariant; P. Delgne’s proof of a function field analogue; p-adic versions of the conjectures due to B. Gross and J.-P. Serre.This volume belongs on the shelf of every mathematics library.