The first part of this book is a course, self-introduction on network calculus. It presents the core of network calculus, and show how it can be applied to the Internet to obtain results that have a physical interpretation of practical importance to network engineers. It is suitable for undergraduate reading and reference source for professionals in the network by way of state of the art survey of research and pointing to open problems in network calculus and its application in various fields, such as mulitmedia smoothing, scheduling aggegate, adaptive guarantees in Internet differential services, service renegotiated reserved, etc.