This multidisciplinary book is intended to serve as a reference for postgraduate students and researchers working in the fields of charged particle optics or other finite-element-related applications. It is also suitable for use as a graduate text. For the non-specialist in charged particle optics, the opening chapters provide an introduction to the kinds of field problems that occur in charged particle beam systems. A new and comprehensive approach to the subject is taken. The finite element method is placed within a wider framework than strictly charged particle optics. Concepts developed in fluid flow and structural analysis, not hitherto used in charged particle optics, are presented. Benchmark test results provide a way of comparing the finite element method to other field-solving methods. The book also reports on some high-order interpolation techniques and mesh generation methods that will be of interest to other finite element researchers. Additional coverage includes: field theory and field solutions for charged particle optics; aspects of the finite difference method related to the finite element method; finite element theory and procedure, including detailed formulation of local and global matrices; higher-order elements, which can be an effective way of improving finite element accuracy; the finite element method in three dimensions; ways to formulate scalar and vector problems for magnetic fields; and significant reduction of truncation errors using higher-order elements and extrapolation methods.