Fluid is a Mac OS X application that lets you package your web applications (GMail, Facebook, Youtube, Flickr, Digg etc) as native Mac OS X desktop applications, complete with own window, standard menu bar, Dock icon and .app program file.
Fluid creates native Mac OS X application that wraps around Apple Safari’s WebKit web rendering engine. The created OS X application is normally referred to as a Site Specific Browser (SSB), which is basically an instance of the browser engine running a specific website URL. This SSB instance runs the web application separately and not from within the web browser. So crashing your browser such as Safari won’t take down your SSB instance.