This is a thorough, yet understandable text about the boundary element method (BEM), an attractive alternative to the finite element method (FEM). It not only explains the theory, but also deals with the implementation into computer code written in FORTRAN 95 (software can be freely downloaded). Applications range from potential problems to static and dynamic problems in elasticity and plasticity. The book also addresses the issue of fast solution of large scale problems, using parallel processing hardware. Special topics such as the treatment of inclusions, heterogeneous domains and changing geometry are also addressed. Most chapters contain exercises and this makes the book suitable for teaching. Applications of the method to industrial problems are shown. The book is designed for engineers and scientists that want to understand how the method works and to apply the method and solve real problems.