This book is the first of a multivolume series devoted to an exposition
of functional analysis methods in modern mathematical physics. It
describes the fundamental principles of functional analysis and is
essentially self-contained, although there are occasional references to
later volumes. We have included a few applications when we thought that
they would provide motivation for the reader. Later volumes describe
various advanced topics in functional analysis and give numerous
applications in classical physics, modern physics, and partial
differential equations.