SharePoint audiences are groups of users selected for some common purpose. For example, a given audience might represent all workers in a given department or all secretaries from all departments. Any given user might belong to any number of audiences.
To limit the audiences to which the current search tab will be shown, enter the name of each approved audience in the Target Audiences field of the Audiences area, with each audience name separated by a semicolon. The current search tab will be shown to all users that belong to at least one of the specified audiences. Leave the Audiences setting blank for any search tab that should appear for all users. See also “Target Audiences in Ontolica” for more information about how to work with audiences and make settings in this area.