High Quality Content by WIKIPEDIA articles! XAML Browser Applications (XBAP, pronounced "ex-bap") are Windows Presentation Foundation (.xbap) applications that are hosted and run 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 like opening a new network connection or saving a file to the computer disk and not all WPF functionality is available. The hosted environment is intended to protect the computer from malicious applications; however it can also run in full trust mode by the client changing the permission. Starting an XBAP from an HTML page 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 (PresentationHost.exe) managed by the CLR. In the initial release of .NET Framework 3.0, XBAPs only ran in Internet Explorer. With the release of .NET Framework 3.5 SP1 which includes an XBAP extension, they also run in Mozilla Firefox.