Stability of structures is one of the most important and interesting fields in mechanics. This book is dedicated to fundamental concepts, problems and methods of structural stability along with qualitative understanding of instability phenomena. It includes modern theoretical and experimental static and dynamic stability studies. It is intended to combine mathematical foundation and interesting classical and modern mechanical problems. The methods presented in the book are constructive and easy to implement in computer programs. Recent exciting experiments on dynamic stability of non-conservative systems are described and shown by many photographs.