We have recently discovered that a perovskite BaSnO3 exhibits high mobility at room temperature when doped with La in the Ba sites. We will go over the mechanism for the high mobility, especially when compared with Sb doping in the Sn sites. We will describe the large effect of threading dislocations on the mobility of epitaxial thin films on SrTiO3 substrates. In addition, a very stable oxygen stoichiometry in BaSnO3 system has been measured. Such high chemical stability promises a large potential for well-defined interface in heterostuctures based on them. To demonstrate in this direction, we will present our current research efforts in pn-junctions and FETs based on the BaSnO3 system. Furthermore, 2DEG based on the BaSnO3 system can shed light on the exact mechanism of 2DEGs found at the interfaces of polar perovskites. We will report on our recent findings in this area as well. Due to high-mobility, chemical stability, and bipolar dopability, the BaSnO3 system promises a large potential for scientific research and technological applications.