| canonical tag | An HTML tag that helps reduce duplicate content. This tag indicates to search engines which page is the preferred version of content that should be ranked. |
| google supplemental index | A secondary database that Google uses to store pages it deems to be of less importance to its main search engine results. |
| co-citation | How frequently two websites (or webpages) are mentioned together by a third-party website, even if those first two items don’t link to (or reference) each other. This is a way search engines can establish subject similarity. |
| meta title | an HTML meta tag that describes a specific web page and often forms the blue linking phrase found on search engine results pages. Should contain keywords associated with the page. Also known as the page title or meta title. |
| yahoo directory | A long-standing, authoritative web directory. Yahoo! Directory does offer paid inclusion to qualified websites. |
