Graphs drawn on two-dimensional surfaces have always attracted researchers by their beauty and by the variety of difficult questions to which they give rise. The theory of such embedded graphs, which long seemed rather isolated, has witnessed the appearance of entirely unexpected new applications in recent decades, ranging from Galois theory to quantum gravity models, and has become a kind of a focus of a vast field of research. The book provides an accessible introduction to this new domain, including such topics as coverings of Riemann surfaces, the Galois group action on embedded graphs (Grothendieck's theory of "dessins d'enfants"), the matrix integral method, moduli spaces of curves, the topology of meromorphic functions, and combinatorial aspects of Vassiliev's knot invariants and, in an appendix by Don Zagier, the use of finite group representation theory. The presentation is concrete throughout, with numerous figures, examples (including computer calculations) and exercises, and should appeal to both graduate students and researchers.

 Sergei LANDO graduated from the Moscow State University in 1977, got the PhD degree from the Moscow State University in 1986 under the supervision of Prof. V.I. Arnold; worked for the Russian Academy of Sciences in 1986-1990 and since 1996 till now; one of the organizers (1991), and currently professor and vice-president of the Independent University of Moscow.

 Alexander ZVONKIN graduated from the Moscow State University in 1970, got the PhD degree form the Moscow State University in 1974 under the supervision of Prof. A.N.Shiryaev; worked as associate professor (1973-1975), as industrial researcher (1975-1988), and in the USSR Academy of Sciences (1989-1992); from 1991 till now, professor of computer science at Bordeaux I University, Bordeaux, France.

0 Introduction: What is This Book About.- 1 Constellations, Coverings, and Maps.- 2 Dessins d'Enfants.- 3 Introduction to the Matrix Integrals Method.- 4 Geometry of Moduli Spaces of Complex Curves.- 5 Meromorphic Functions and Embedded Graphs.- 6 Algebraic Structures Associated with Embedded Graphs.- A.1 Representation Theory of Finite Groups.- A.1.1 Irreducible Representations and Characters.- A.1.2 Examples.- A.1.3 Frobenius's Formula.- A.2 Applications.- A.2.2 Examples.- A.2.3 First Application: Enumeration of Polygon Gluings.- A.2.4 Second Application: the Goulden-Jackson Formula.- A.2.5 Third Application: "Mirror Symmetry" in Dimension One.- References.