BASIC is a programming language invented in 1964. Dozens of versions exist because BASIC was customised for numerous microcomputers in the 1970s. Microsoft introduced Microsoft BASIC in 1975 and it became the industry standard, eventually used by Apple, Commodore and Tandy. Code is typed into your computer from a magazine or book and saved into memory then run. It was often necessary to delete as many lines of code as possible because computers only had a few KB of memory.