Aerospace structures are commonly subjected to vibrations during operation. For analysis and design purposes it is critical to model the response of a structure under free and forced loading conditions. This course is an introduction to vibrations in structures and covers the following topics: 1. Introduction to vibrations and modelling of structures. 2. Free vibrations in single degree-of-freedom models. 3. Harmonically forced vibrations. 4. Vibrations under general loading types: impulse loading, step loading, arbitrary transient loading. 5. Vibration concepts: eigenfrequency, resonance, critical, undercritical and overcritical damping, transfer function. 6. Multiple degree-of-freedom systems.