The book gives a detailed and comprehensive description of the dynamic behaviour of hydraulic automotive damper modules (consisting of the damper and its top mount). It is shown that the damper elasticity in combination with non-linear force characteristics is responsible for the dynamic damper property. The physical nature of this elasticity is explained in detail. Using methods of linear system theory new parameters will be introduced, characterising the damper behaviour at different frequencies. The use of these parameters can be extended to non-linear force characteristics. The new parameters are well defined even for non-linear force characteristics and easily measurable for all dampers. Another topic of the book is the interaction between the damper and the top mount. The physical nature of parameter-excited vibrations (often causing a comfort destroying noise in passenger cars) of the piston rod mass is revealed and a new mechanical principle is given to avoid such vibrations. General hints for the mutual design of these force elements are given and a specialised optimisation procedure for the force characteristics of damper modules is applied. It is shown, that the use of a top mount in damper modules does not only reduce the vibration isolation at higher frequencies but also increases ride safety. That completes the investigation of the inner and out damper elasticity to give a comprehensive explanation of the vertical dynamics of damper and top mount vibration behaviour.