This section of the book deals with the accuracy of gears, and of the impact of the gear accuracy onto the noise emission and vibration generation when the gear transmission is operated. Here, in this text, the accuracy of the gears themselves and the accuracy of the gear configuration in relation to one another are covered by the term “gear accuracy.” A variety of the root causes for the displacements of the gear axes of rotation are considered. To attract the readers’ attention to a complex problem of gear noise and vibration is the main goal of the text below.