This introduction to the study of vibrations and waves is very much focused on mechanical systems. So, a good working knowledge of elementary kinematics and dynamics is advised. The decision to limit the scope of the book in this way was guided by the fact that the presentation is quantitative and analytical rather than descriptive. The temptation to incorporate discussions of electrical and optical systems was always strong, but it was felt that a great part of the language of the subject could be developed most simply and straightforwardly in terms of mechanical displacements and scalar wave equations, with only an occasional allusion to other systems.