Cygwin (pronounce /ˈsɪɡwɪn/) is a collection of tools originally developed by Cygnus Solutions to allow versions of Microsoft Windows to behave in ways familiar to Unix users. Programs supported by Cygwin work well on Windows NT, Windows 2000, Windows XP, Windows Vista and some run acceptably on Windows 9x. While Cygwin provides header files and libraries that make it possible to recompile or to port Unix applications for use on computers running Microsoft Windows operating systems, it does not make binaries compatible with such computers running without Cygwin.