Over the years, the construction of models has played an important part in the discovery and dissemination of knowledge. The study of problems involving the coupling of several systems has been widely explored, essentially in the function of the change of constructive characteristics of machines and structures. Accordingly, vibrating (oscillatory) processes can be divided into the following types: free, forced, parametric, and self-excited oscillations. Furthermore, two or more oscillations can interact in the same oscillatory system. This book provides a comprehensive overview of oscillators and their applications. It includes eight chapters organized into three sections "MEMS and NEMS", "Vibrations" and "Modeling".