In 2008 the Planck satellite will be launched. The following 1-2 years it will provide temperature and polarization data of the cosmic microwave background (CMB) with extremely high resolution and sensitivity. By analyzing these data, several cosmological parameters may be estimated with unprecedented precision. But new experiments to be conducted after Planck are already planned. I will discuss why we need these experiments and we will see that one of the most important discoveries in cosmology ever could actually be made, not by Planck, but one of the post-Planck experiments. The first part of the seminar will be an introduction to CMB and CMB experiments for beginners, so all experts are allowed to come late :)