A family of standard web feed formats used to publish frequently updated information like blog entries, news headlines, audio and video.
Allows a website to define how a page is rendered in Internet Explorer 8, allowing a website to decide to use IE7 style rendering over IE8 rendering.
Open graph description entity tag
A WebSite is a set of related web pages and other items typically served from a single web domain and accessible via URLs.
Sites who has this tag are verfied by google to use WebMaster tools