Typewriter-style fonts are best for program listings, but Computer Modern Typewriter prints ` and ' as bent opening and closing single quotes. Other fonts, and most programming languages, print ` as a grave accent and ' upright; ' is used both to open and to close quoted strings. The package switches the typewriter font to Computer Modern Typewriter in OT1 encoding, and modifies the behaviour of verbatim, verbatim*, \verb, and \verb* to print in the “` and ' way”. It does thisregardless of other fonts or encodings in use, so long as the package is loaded after the other fonts were. The package does not affect \tt, \texttt, etc.