This book is designed primarily for end users and application developers. It is also intended for those who run parallel programs, and some of the information and tools covered should interest system administrators. Readers should have some experience with graphical user interface concepts such as windows, pull-down menus, and menu bars. They should also have knowledge of the AIX operating system and the X-Window system. Where necessary, this book provides some background information relating to these areas. More commonly, this book refers you to the appropriate documentation.