The National Radio Institute-McGraw Hill Continuing Education Center was a private post-secondary for-profit school, specifically a correspondence school, based in Washington, D.C., in business from 1914 to 2002. It originally trained students desiring to become radio operators and technicians. In 1922, the term "radiotrician" was coined for NRI graduates and registered with the U. S. patent office in 1928. NRI conducted its training courses through mailed lessons, a form of asynchronous learning. The first such home-study courses NRI offered were in radio repair (transmitters and receivers) and radio telegraphy & telephony. These courses were designed to be comprehensive, covering all facets of radio technology, including: radio operation, broadcasting, manufacturing, sales, and service.