In cleanrooms, there are various types of contamination that must be avoided at all costs. The lecture will define and describe these different types of contamination in detail. Additionally, it will address the main source of all contamination—the human being. Furthermore, important behavioral guidelines for cleanroom personnel to follow in order to effectively prevent contamination will be outlined. Finally, the lecture will comprehensively cover the different clothing requirements depending on the type of cleanroom and the specified cleanliness class.