Lint was a program which literally exmined K&R C SourceCode for "lint" -- bits of fluff in the code. Lint was necessary because prior to ANSI C, the language was much looser about what it accepted, arguments and variables could have implicit types and there were a range of other conveniences. Lint performed SourceCode checking in an era when Compilers didn't. With modern Compilers, Lint's function is performed by simply compiling with all the warning flags turned on (i.e. -Wall).