How you define Mashups in Ajax?
Ajax Mashup is an hybrid web application.
Ajax Mashup uses Ajax techniques to present a rich UI that can updates itself in place by using content that it retrieves asynchronously from multiple sources.
In this server sends an initial page to the browser, which then makes calls to retrieve updated content. These calls are used to made directly to the third-party sources from the browser or back to the originating server, It is act as a proxy for the third-party content.