Microcomponents and microdevices are increasingly finding application in everyday life. The specific functions of all modern microdevices depend strongly on the selection and combination of the materials used in their construction, i.e., the chemical and physical solid-state properties of these materials, and their treatment. The precise patterning of various materials, which is normally performed by lithographic etching processes, is a prerequisite for the fabrication of microdevices. The microtechnical etching of functional patterns is a multidisciplinary area, the basis for the etching processes coming from chemistry, physics, and engineering. The book is divided into two sections: the wet and dry etching processes are presented in the first, general, section, which provides the scientific fundamentals, while a catalog of etching bath composition, etching instructions, and parameters can be found in the second section. This section will enhance the comprehension of the general section and also give an overview of data that are essential in practice.