1. One or more non-transitory computer-readable media storing instructions which, when processed by one or more processors, cause: a Web application generating and transmitting to a client device over one or more networks, a first set of one or more Web pages which, when processed by a Web browser at the client device, provide a graphical user interface that allows a user to specify an advanced search query that includes one or more search terms and one or more logical custodians; the Web application causing the advanced search query to be processed against a plurality of data items to generate a set of search results; and the Web application transmitting to the client device over the one or more networks, a second set of one or more Web pages which, when processed by the Web browser at the client device, provide a graphical user interface that displays the set of search results.