Do you want to search only a particular website or it’s sub domain for a info? Google Advanced Search Operator site: will help you to find information about anything in a site and or its sub domain. For example if you want to search article related to swine flu in webmd.com, use swine site:www.webmd.com
Search box in some web sites is not working as expected, so site: operator will search entire site for the passed term. Twitter site:www.thepicky.com will search ThePicky.com for Twitter info.
If you use site:edu, this will restrict search results to the only educational sites. for ex admission site:edu will search all educational sites for admission information.