The current monograph is designed for the students of technical universities and higher education institutions as well as for the staff in technical practice. Degradation processes have very different influences on materials since the latter are highly diverse. Study of degradation processes can improve utilisation properties of materials based on their usability. This publication can help to understand some types of degradation processes performed on different materials. Introductory sections characterise the basic types of structural materials, degradation process and limit state of materials. The influence of elastic and plastic deformation to material properties is important in their treatment. Many parts are worn during their exploitation, and therefore the wear mechanisms is characterised in the next sections. Certain chapters are dedicated to the fundamentals of fracture mechanics and fractography of fracture surfaces, and described is the influence of fatigue, creep or corrosion to material degradation processes. Other degradation influences on technical materials, such as ceramics, glasses, plastics or composite materials are also described. Theoretical findings are complemented by a variety of real-life examples of various damaged components and structures. Listed are also solutions to the problems in terms of prediction of the service life of materials. Knowledge about degradation processes on materials is very important for appropriate design of functional parts exploited under various loads, environments or temperatures that limit the usability of materials for some applications. Currently, there is a wide scope of knowledge and analytical techniques that can be used in the optimization of material solutions for specific parts.