| banner blindness | The idea that users have been so inundated with advertisements they now ignore ads in traditional positions (banners along the top or down the side). This is a big reason for text and other contextual advertising achieving greater success. |
| mashup | Noun. A page made up from gizmos (or mostly from gizmos). The gizmos could be RSS feeds, Javascript feeds, etc. Any content pushed by free content distribution sites. Google maps is a great gizmo. |
| backlink tool | A tool that helps you check and analyze backlinks going to a website. |
| header tags | An HTML element used to designate headings on your page. |
| authority site | An authority site is a particularly high quality website. An authority site could technically be a commercial website that is the authority on a topic, though for many SEOs in certain contexts (ie for the purposes of writing an article) an authority site is generally considered to be either governmental, an association, or otherwise neutral from a commercial perspective. |