The California Institute of Technology (called "Caltech" for short) is a major American research university in the city of Pasadena in the state of California. Caltech specializes - is especially good, or especially interested - in the study of engineering, computer science, and the physical sciences (some physical sciences are physics and chemistry, as well as others). Caltech is also in charge of the Jet Propulsion Laboratory, also called JPL. JPL is part of NASA, the National Aeronautics and Space Administration, which is the part of the United States government that explores space. Caltech is not owned or run by the United States, or NASA, but NASA pays Caltech to run JPL for them. By most measures, it is the most selective college/university in the world and has one of the highest faculty-to-student ratios in the world.