RPG is a high-level programming language for business applications, introduced in 1959 for the IBM 1401. It is most well known as the primary programming language of IBM's midrange computer product line, including the IBM i operating system. RPG has traditionally featured a number of distinctive concepts, such as the program cycle, and the column-oriented syntax. The most recent version is RPG IV, which includes a number of modernization features, including free-form syntax.