Meta tags in HTML documents provide useful information about the document including a description, keywords, author, dates of modifications and around 90 other fields. This topic covers the usage and purpose of these tags.
<meta name="metadata name" content="value">
<meta http-equiv="pragma directive" content="value">
<meta charset="encoding label">
The meta tag is an HTML tag used to set the metadata of the HTML document. Meta tags need to go in the head element. A page may have any number of meta tags.
The meta tag
keywords is not typically used by robots. Most search engines determine what keywords fit with the content on the web pages. That being said, nothing says you should no longer include the keywords meta tag.
The meta data of a page is mostly used by the browser (like the scaling of a document) and web crawling spiders used by search engines (Google, Yahoo!, Bing).
The spec gives a number of standardized metadata names for use with
<meta name> and standardized metadata pragma directives for use with
<meta http-equiv>. However, many services across the internet (web crawlers, authoring tools, social sharing services, etc.) use the
<meta name> form as a generic extension point for metadata. Some of these are listed on the spec's wiki page.