The present volume addresses the application of asymptotic methods in nlinear oscillations. Such methods see a large variety of applications in physics, mechanics and engineering. The advantages of using asymptotic methods in solving nlinear problems are firstly simplicity, especially for computing higher approximations, and secondly their applicability to a large class of quasi-linear systems. In contrast to the existing literature, this book is concerned with the applied aspects of the methods concerned and also contains problems relevant to the everyday practice of engineers, physicists and mathematicians. Usually, dynamics systems are classified and examined by their degrees of freedom. This book is constructed from ather point of view based upon the originating mechanism of the oscillations: free oscillation, self-excited oscillation, forced oscillation, and parametrically excited oscillation. The text has been designed to cover material from the elementary to the more advanced, in increasing order of difficulty. It is of considerable interest to both students and researchers in applied mathematics, physical and mechanical sciences, and engineering.