Meta Keywords - What are, Should we use ?!
Meta elements are typically used to specify page description, keywords, author of the document, last modified, and other metadata.
Meta Keywords in Head of HTML Document
Keywords Header Email Usage and Keyword Research
Meta keywords should not be ignored, though they are not a major ranking factor for most of the search engines nowadays. A Meta keywords tag is supposed to be a brief and concise list of the most important themes of your page.
Read also:
Create description meta tag for SEO
Page titles and SEO
Keep your list of keywords or keyword phrases down to 10 - 20 unique words or phrases.
Separate the words or phrases using a comma (you do not need to leave a space between words separated by commas).
Do not repeat words or phrases.
Put your most important word or phrases at the beginning of your list.
Differences Between HTML and XHTML
In HTML the <meta> tag has no end tag.
In XHTML the <meta> tag must be properly closed.
<meta name="keywords" content="HTML, CSS XML, XHTML, JavaScript">
The keywords attribute was utilized by search engines to provide more accurate search results. Due to the over usage and spamming the keywords attribute has been phased out and is no longer relevant. Google doesn't use the "keywords" meta tag in web search ranking.
The keywords attribute was popularized by search engines such as Infoseek and AltaVista in 1995, and its popularity quickly grew until it became one of the most commonly used meta elements.
in September 2009 Matt Cutts of Google announced that they were no longer taking keywords into account whatsoever.
However, Yahoo! still, takes use of the keywords meta tag in some of its rankings. Yahoo! itself claims support for the keywords meta tag in conjunction with other factors for improving search rankings.