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.