Abstarct: In this dissertation, several generalizations of unique factorization domains and their behaviour in localization and polynomial extension is studied. These classes are, half factorization domains (HFD), bounded factorization domains (BFD), finite factorization domain (FFD), idf-domains, ACCP domains and atomic domains. Using a variety of counter-examples, the relations between these classes are determined. Then, the stability of these properties under localization is studied. Although in general none of these classes ascend or descend under localization, but it will be shown that these properties become stable under some additional conditions. The same thing is done for polynomial extensions afterwards. It will be shown that, all of these properties descend in polynomial extensions and in addition, the classes ACCP, BFD and HFD ascend in polynomial extension. Also, using directed unions, these results will be generalized to polynomials with arbitrary number of variables. Finally, the ascend of HFDs, ACCP domains and atomic domains under polynomial extension is studied and in particular, counter-examples will be found, showing that none of these classes ascend in polynomial extensions in general.