There are different types of contamination in cleanrooms that need to be avoided. As part of the lecture, the different types of contamination are defined, described and explained. In addition, the main source of all contamination - people in the cleanroom - is discussed. Furthermore, rules of conduct that staff should observe in the cleanroom in order to avoid contamination are described. Finally, the various clothing regulations depending on the type of clean room and the air purity class are explained.