I will provide an introduction to class forcing that focuses on the notion of pretameness. 

This property was introduced by Sy Friedman in order to characterize the preservation of the axioms of ZF^-, that is ZF without the Power Set axiom, in class forcing. 
We will provide several further characterizations of pretameness and investigate possible bad behaviour of non-pretame class forcing. 

This is joint work with Regula Krapf and Philipp Schlicht.