Web Applications are web sites that perform the same function as software that you might otherwise download and run locally. Having the advantage of executing on a web server, Web Applications don't consume space on your hard drive, don't crash or conflict with other applications, and best of all are accessible from anywhere.

The downside from the end user's point of view is loss of control over what the application does, the impossibility to keep old versions and possible privacy problems.

The companies that create and serve web applications are called Application Service Providers (ASPs).