Roff is a Unix typesetting markup language and predecessor to nroff and troff, descended from RUNOFF programs created for earlier systems like CTSS and Multics. Ken Thompson transliterated it into PDP-7 assembler around 1970, then again into PDP-11 assembly in 1971, where it formatted Unix man pages and became the first Unix application used by Bell Labs' patent department, helping secure funding for early Unix hardware.