HTML - Meta Tags and Meta Data
Meta tags are used to supply information for search engines that will not be seen by the web surfer. These invisible units provide a flag for search engines to investigate and will then present that data to any potential users that stumble across your site through a search engine.
In the past, meta tags were the primary means for your site to be recognized by web spiders, but webmasters abused meta tags to improve their rankings in search engines. As a result, search engines have since modified their approach to keep results accurate. They now rely less on meta tags. Nevertheless, you should still include meta for those search bots that still do recognize them.
HTML - Meta Tag Description
Search engines are the compasses of the web and help users navigate from site to site. Chances are, if you've used a search engine, you've probably seen the description meta tag in action.
Meta elements must be placed inside of the <head> element in order for them to be recognizable by web crawlers and bots. The <meta> tag generally requires the name and content attributes to be working together to present your web page in a good light.
<meta name="description" content="My It World contains webmaster tutorials." />
The description meta element allows the developer to summarize the content that can be found on the page and is often the first chance you'll have to attract visitors. These brief narratives and hooks are often the only opportunity you'll have to generate a lasting first impression.
HTML - Keyword Meta Tags
Keywords and/or phrases may be placed inside the keyword meta element. You should specify the most popular search terms you believe someone would use to reach your website. A few years back, you could spam this meta tag with any and every keyword possible to gain ranking on search engines. Now, however, repeated words, or words that do not pertain to the content of the site, will not benefit your search engine rankings.
<meta name="keywords" content="keyword, key keywords, etc" />
Separate each phrase/word with a comma to create large lists. An example of the keywords meta tag for Tizag.com would go something like this:
<meta name="keywords" content="HTML, XHTML, CSS, tutorials, My It World" />
Keep in mind that driving traffic and having your site listed high in the search engine rankings is not as easy as placing keywords inside your meta element. The phrase "Search Engine Optimization (SEO)" was coined to describe the rigorous process involved in achieving rankings in search engines. While meta tags do play a small role in this process, they are by no means a one-stop shop for your SEO needs.