A general study of functional equations in normed spaces is made in this book, with special emphasis on approximative methods of solution. The subject is covered in two parts; the first is notable for the thoroughness of the treatment at a level suitable for immediate post-graduate students. It contains a detailed account of the theory of normed spaces with a final chapter on the theory of linear topological spaces. The second part is suitable for reference or for group research studies in specifically defined fields. It takes up the theory of the solution of a wide class of functional equations, and continues with the development of approximative methods, both general and specific. This aspect of the subject is profusely illustrated by particular examples, many drawn from the theories of integral equations and differential equations, ordinary and partial.