This is the central unit of the course - we quantize universal enveloping algebras and their duals. Central discussion is the fact that for the first type of Hopf-algebras the deformation of the coproduct is sufficient and for the second type it is the dual multiplication. This motivates the way quantization is performed in particular and how this gives rise for noncommutativity for the module and comodule spaces that are so interesting for physics. Currently most popular way to quantize universal enveloping algebras is the twisting according to Drinfeld. We discuss how and why this is such a good concept.