A programming language designed initially by the IBM users’ group SHARE, and adopted by IBM as a major product. PL/I was intended to replace all pre-existing programming languages, incorporating the best features of Cobol, Fortran, and Algol 60. The resulting language is large and complex: it was taken up by only a few other companies, and has had only limited acceptance among IBM users.

PL/I was adopted as a teaching language by a number of universities, notably Cornell, who produced their own versions, PL/C and PL/CT. It was also used as a basis for the microcomputer language PL/M.