Mac OS X applications have an ".app" extension. They are similar to .EXE files found on Windows computers and contain executable code that runs when the file is opened.

APP files are saved in a package format, which contains the program data and resource files. You can view the contents of an application package in Mac OS X by right-clicking an APP file and selecting "Show Package Contents" from the contextual menu.

Software program written for the Symbian OS, an operating system for mobile phones and smartphones; includes phones from Nokia, Sony Ericsson, Samsung, and FOMA.

Application used by FoxPro to automate procedures (i.e. creating new label sizes, transforming data values, analyzing code, etc); may be included with FoxPro or custom built by the user from a project (.PJX) file using the BUILD APP command