A portable application (portable app), sometimes also called standalone, is a program designed to read and write its configuration settings into an accessible folder in the computer, usually the folder where the portable application can be found. This makes it easier to transfer the program with the user's preferences and data between different computers. A program that doesn't have any configuration options is also a portable application.
Portable applications can be stored on any data storage device, including internal mass storage, a file share, cloud storage or external storage such as USB drives and floppy disks—storing its program files and any configuration information and data on the storage medium alone. If no configuration information is required a portable program can be run from read-only storage such as CD-ROMs and DVD-ROMs. Some applications are available in both installable and portable versions.
Some applications which are not portable by default do support optional portability through other mechanisms, the most common being command-line arguments. Examples might include /portable to simply instruct the program to behave as a portable program, or --cfg=/path/inifile to specify the configuration file location.
Like any application, portable applications must be compatible with the computer system hardware and operating system.
Depending on the operating system, portability is more or less complex to implement; to operating systems such as AmigaOS, all applications are by definition portable.