HTML Meta tags were originally designed to provide information to browsers and search engines. Many different Meta tags evolved in the early days of the Internet, but due to widespread abuse, many are ignored by search engines today and are therefore useless. Others have been rendered obsolete due to browser evolution.
As a general rule, you should not use an HTML Meta tag unless it serves a purpose. Useless Meta tags add unnecessary overhead to a Web page and pushes content further from the top of a script. Useless code must be downloaded along with useful code, and if you are trying to improve the performance of your Web pages, you need to eliminate everything that is not needed. When content is pushed further from the top of a script, it holds less relevance to a search engine.
Unnecessary Meta tags find their way into scripts because some designers believe they are beneficial. They are most likely basing this on information that is several years old. Five years ago the Keywords Meta tag was extremely important. Today the Keywords Meta tag has only
minimal value, if any, due to widespread abuse by site owners and the natural evolution of search engines. Some WYSIWYG Web design tools allow a designer to easily add Meta tags to a page, and a few naive designers take the "more is better" approach.
Some online HTML Meta tag generator tools are useful to help you to understand how to use Meta tags, while other are not. I have seen at least one online tool that generates a long list of customized Meta tags and assures users that this will help boost their rankings in search engines.
This is utter nonsense and such advice has no merit.
There is a class of meta tags that never has served any purpose other than providing information to a site owner or designer. These tags are therefore useless for search engines and browsers and therefore should not be used.
Useful Meta Tags
<meta name="description" content="An article that explains how to identify when a Web site has been penalized by Google.">
The Description Meta tag is the most useful of all and should be included on every Web page. The Description Meta tag shows up as the description for a Web page on most search engine results pages (SERPs). While it will not necessarily help you with search engine rankings, it is a powerful marketing tool that can be the determining factor when a user is deciding whether to click on your link or one of nine others on a SERP. The Description Meta tag should be unique for each page in your site and should accurately describe the contents of the page. The description itself should also be compelling.
<meta name="keywords" content="bad neighborhood, penalized site, webmaster guidelines">
The Keywords meta tag is not used by the major search engines, but is used by some smaller search engines. It it therefore worthwhile to include it if you want your site to appeal to a wide range of search engines. If you do decide to use it, every phrase listed in this Meta tag should appear on the page or you risk a penalty with the search engines that use it.
<meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="pragma" content="no-cache">
These cache related Meta tags prevent browsers from caching pages. This means the HTML script will not be stored by the browser. Caching is used by browsers to speed up the rendering of a Web page upon subsequent visits. These Meta tags are useful on pages where the content changes often. One version works for older browsers, while the other works for newer browsers and thus they are most effective when used in tandem.
<meta name="robots" content="index,follow"> <meta name="robots" content="index,nofollow"> <meta name="robots" content="noindex,follow"> <meta name="robots" content="noindex,nofollow"> <meta name="googlebot" content="noarchive">
The robots meta tag is used by search engine spiders to determine if the page should be searched for keywords and content (index/noindex) and if the hyperlinks on the page should be followed (follow/nofollow). The first version is technically the default for any page that does not
contain this Meta tag and is therefore serves no real purpose. The next three each serve a distinct purpose, depending upon what you want a spider to do. If you do not want a spider to index the page, include the "noindex" value in the content attribute. If a section of a Web site needs to be protected from spiders, use the "noindex,nofollow" values on each page in the protected section. This does not absolutely protect a page from being indexed. Sometimes the search engine spiders do not follow the rules.
<meta name="robots" content="noarchive">
If you do not want the spiders to cache (archive or store) a copy of a Web a page, there is a noarchive value that can be used.
<meta name="googlebot" content="noindex">
Google offers a googlebot Meta tag as an additional protection to prevent the Google spider (called googlebot) from indexing a page. Use of this meta tag would only affect Google spiders and not spiders from MSN or Yahoo.
<meta http-equiv="imagetoolbar" content="no"> <meta http-equiv="imagetoolbar" content="false">
This Microsoft Meta tag is useful for preventing the annoying image toolbar from displaying when a user moves their mouse pointer over an image when using current version of Internet Explorer. Either version will work.
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <meta http-equiv="Content-Language" content="en-us">
The character set and language Meta tags may be useful for foreign
browsers whose defaults are set to different character sets and
Meta Tags That Are Ignored by Search Engines and Browsers
<meta http-equiv="reply-to" content="firstname.lastname@example.org"> <meta name="robots" content="all"> <meta name="revisit-after" content="15 Days"> <meta name="resource-type" content="document"> <meta name="classification" content="Internet"> <meta name="distribution" content="Global"> <meta name="rating" content="General"> <meta name="doc-class" content="Completed"> <meta name="generator" content="Microsoft FrontPage 4.0"> <meta name="classification" content="Advertising and Marketing"> <meta name="MSSmartTagsPreventParsing" content="true"> <meta name="copyright" content="John Doe Web Design"> <meta name="author" content="John Q. Public"> <meta name="doc-type" content="Web Page"> <meta name="doc-class" content="Published"> <meta name="doc-rights" content="Public">
Remember, the general rule is to avoid using a Meta tag unless it serves a specific purpose. If you do not find a specific Meta tag listed here, do some research and see if has any real value before you add it to a Web page.