The Chicago School, or the Chicago School of Economics, refers to a specific style of thought originating from the University of Chicago. Starting in 1970s, professors at the school developed a certain set of economic theories. Most prominent of these thinkers was Milton Friedman, who won a Nobel Prize in 1976 for his theory on unemployment.
You probably shouldn't try to boil down a Nobel Prize-winning economic program into a few sentences. But we're going to try. The basic principle boils down to this: markets manage better without government interference. The Chicago School argues that with government interference comes monopolies and uneven demand.