This book introduces the basic ideas to build discontinuous Galerkin
methods and, at the same time, incorporates several recent mathematical
developments. The presentation is to a large extent self-contained and
is intended for graduate students and researchers in numerical analysis.
The material covers a wide range of model problems, both steady and
unsteady, elaborating from advection-reaction and diffusion problems up
to the Navier-Stokes equations and Friedrichs' systems. Both finite
element and finite volume viewpoints are exploited to convey the main
ideas underlying the design of the approximation. The analysis is
presented in a rigorous mathematical setting where discrete counterparts
of the key properties of the continuous problem are identified. The
framework encompasses fairly general meshes regarding element shapes and
hanging nodes. Salient implementation issues are also addressed.