Title: Many-body localization Abstract: Many-body localization is a phenomenon in physics where a material fails to conduct any heat at all. One could say it is a regime of extreme validity of the KAM theorem (folk wisdom has it that KAM theory is only applicable for systems with a few degrees of freedom, but in quantum mechanics there are good reasons to believe that it can apply to systems in the thermodynamic limit as well). From the point of view of mathematics, localization is in fact much more accessible than basically any other phenomenon in condensed matter physics. Our recent work (joint with F. Huveneers) on this has been mostly non-rigorous. Depending on hints from the audience, I will either try to give a conceptual introduction or to discuss some of our work.