Portability

Portability is the characteristic of a computer program that can be run on different processors or under different operating systems or within different display paradigms with little or no implementation differences, sources of user confusion or other bad stuff.

The data compression programs Zip and Unzip are often held to be amongst the most portable and most ported, due to being a simple front end to a mathematical algorithm. Another more complicated but highly portable programs is VIM, or Vi IMproved: available in MS-DOS, Win16, Win32 (in graphical and text-only modes), MacOS 7.0 and OS X, BeOS and pretty much any flavour of Unix.