(1) An application that can be converted from one computer environment to another. See
software portability and
port.
(2) An application that can be easily moved from one computer to another. With Windows, such programs would not use the Registry. In a totally portable program, all related files might be stored within one folder for ease of copying. See
Registry and
folder.
(3) An application stored on a USB flash drive that can run on a computer without leaving any trace when the operation is finished. A portable app is designed to restore all changed settings when it is closed. See
U3 and
Windows To Go.