Inner functions form an important subclass of bounded analytic
functions. Since they have unimodular boundary values, they appear in
many extremal problems of complex analysis. They have been extensively
studied since early last century, and the literature on this topic is
vast. Therefore, this book is devoted to a concise study of derivatives
of these objects, and confined to treating the integral means of
derivatives and presenting a comprehensive list of results on Hardy and
Bergman means. The goal is to provide rapid access to the frontiers of
research in this field. This monograph will allow researchers to get
acquainted with essentials on inner functions, and it is self-contained,
which makes it accessible to graduate students.