XAML Browser Applications

XAML Browser Applications (XBAPs) are programs that are hosted inside a web browser such as Firefox or Internet Explorer. Hosted applications run in a partial trust sandbox environment, and are not given full access to the computer's resources and not all WPF functionality is available. The hosted environment is intended to protect the computer from malicious applications. Starting an XBAP (pronounced "ex-bap") from an HTML page or vice versa is seamless (there is no security or installation prompt). Although one gets the perception of the application running in the browser, it actually runs in an out-of-process executable managed by the CLR. As of the release of .NET Framework 3.0, XBAPs only run in Internet Explorer. With the release of .NET Framework 3.5 SP1 which includes the an XBAP extension, they also run in Mozilla Firefox.