What is an app?

Answers to the question "what is an app", and definitions of app, application, application suite, app store, and killer app.

The short answer: App is short for "application," a software program that performs a (usually) useful function such as word processing; a tool provided by a computer that performs a task to benefit the user.

Background, history, and more detail:

The lowly abbreviation "app" has been around for decades but has found much attention of late when Apple opened its "App Store" for the iPhone and iPod Touch in July, 2008. Soon, other handset manufacturers and cellular carriers opened their own app stores, hoping customers would purchase, download and install the small pieces of software for a fee. Perhaps the shortened version of "application" is more desirable by marketing types to impart the fact that this software is meant for smaller devices. In any case, "app" can refer to the tiniest, least functional iPhone app (SimStapler anyone?) all the way up to the most complex 3D drafting program such as AutoCAD.

In everyday use, however, most people are familiar with applications such as Microsoft Word and Excel to produce documents and spreadsheets. Not all software, however, is application software. The software that basically runs your computer (or phone) is called an "operating system" such as Microsoft Windows or Linux. Applications typically need an operating system on which to run, but in some cases, the application becomes embedded in the operating system. This is usually only the case in stand alone equipment, such as a microwave oven or a DVD player. Believe it or not, the software that runs these types of devices can also be considered an application.

The files that are produced by applications, such as a Word document or Excel workbook are not considered applications. These are typically referred to as documents. The distinction here is that the documents on their own have very little use. The application software is necessary in order to utilize the document. A typical "doc" file would be virtually useless without the Microsoft Word application to view or edit the file. This difference is often visually represented by the icons used for such files. Application icons are typically more ornate, with some indication of an action taking place. Document icons, on the other hand, tend to be bland and often have some representation of text or writing within them.

Can you guess which icon above represents an application?

So we have seen how application software performs a task for the user and often generates document files. Here are some other app-related terms:

App Store

Although the Apple "App Store" appears to be the most well-known source for purchasing small software applications for a phone, they are neither the only nor the first to do so. In 2001, Sprint PCS and Nextel Communications began selling Java-based applications for their handsets. In 2002, Verizon began selling "BREW" (Binary Runtime Environment for Wireless) based applications for their phones under the "Get It Now" service. Although these services can be considered "app stores" they differ from the current Apple model in some significant ways. The main difference is that Apple only needs to support one type of device from one manufacturer (themselves) resulting in full compatibility of features. Other carriers support many different phones and the same app may result in a different experience on each phone. In addition, these older apps often do not take advantage of the new features built into a modern phone like the iPhone, such as GPS and accelerometers.

Killer App

Simply put, a killer app is a software application that is so beneficial or useful, that it alone justifies purchasing the hardware that the app requires to run. For example, the killer app for the Mac was originally (and is still often) desktop publishing tools such as Pagemaker and Illustrator. These apps were so useful that the Mac was often purchased due to the strength of just one of these programs. For the PC, the Lotus 123 spreadsheet program is generally regarded as the killer app for that platform. Until the release of Lotus, sales of the IBM PC were relatively slow.

Application Suite

An application suite is a group of complemetary programs that are bundled or sold together. Microsoft Office (which usually includes Word, Excel, Powerpoint, etc...) is one example of an application suite. In many cases, the software that comprises an application suite may share common functionality or user interface features.

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