AJAX : What is Mashups in AJAX?

An Ajax mashup is a hybrid Web application. It uses Ajax techniques to present a rich UI that updates itself in place using content that it retrieves asynchronously from multiple sources. The server sends an initial page to the browser, which then makes calls to retrieve updated content. These calls can be made directly to the third-party sources from the browser or back to the originating server, which acts as a proxy for the third-party content.