Public specification of a preferred URL for a page allows search engines to understand the original location for content.
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.
The Open Graph protocol enables any web page to become a rich object in a social graph, a open protocol supported by Facebook
Twitter cards make it possible for you to attach media experiences to Tweets that link to your content.
The DOCTYPE is a required preamble for HTML5 websites.
This page contains tags that are specific to an HTML 5 implementation.
A way to make Web content and Web applications more accessible to people with disabilities. It especially helps with dynamic content and advanced user interface controls developed with Ajax, HTML, JavaScript, and related technologies.
The page shows content with an iframe; an embedded frame that loads another webpage.
The defer attribute gives a hint to the browser that the script does not create any content so the browser can optionally defer interpreting the script. This can improve performance by delaying execution of scripts until after the body content is parsed and rendered.
JavaScript is a scripting language most often used for client-side web development.
Cascading Style Sheets (CSS) is a stylesheet language used to describe the presentation of a document written in a markup language. Its most common application is to style web pages written in HTML
JSON-LD, or JavaScript Object Notation for Linked Data, is a method of transporting Linked Data using JSON.