What is a Meta Tag?
A specific kind of HTML tag that contains information not normally displayed to the user. Meta tags contan information about the page itself, hence the name ("meta" means "about this subject")
 
Typical uses of Meta tags are to include information for search engines to help them better categorize a page .Meta tags don't do anything to the content that is presented in the browser window, but they are used by search engines to catalogue information about the web page
 
.Meta tags are a part of HTML that the surfer never sees. They are not included for the surfer's benefit and their contents are not printed to the screen. The main use of meta tags is to provide information for the search engines to use when evaluating a page's content. In recent years, meta tags have become less important in the algorithms of major search engines.

Why are meta tags important? Meta tags are important for search engine optimisation for a couple of main reasons.    The first being that some search engines still use the contents of the keywords and description tags as a factor used to help determine the content of the page.

Some search engines use the contents of the description tag to display the snippet of information about the page in their search results page.There are many meta tags that can be used - the following are the main ones which almost all web site designers incorporate into their website design.

Meta Tag - Title
The title meta tag gives the web page a name to identify it on search engines, and often also gets used when your bookmark a website or add it to your favourites list. Many sites use the companies business name in the metatags which is fine to get the site found on a search for "Smith & Sons", but not if you want to be found by new customers who are searching for your specific products or services. It is more useful to include the keywords you are trying to target in your title, preferably at the start, as this carries weight with the search engines.
 
Meta Tag - Description
The description meta tag should contain your description of your web page. The description is sometimes used by the some of the search engines when they list your webpage in their search results. You should make sure that you include your main keywords within the description metatags.

The Keywords meta tags are where you list those words or terms you want to be found under.

Meta Tag - Keywords
Some search engines still use keywords as part of their strategy to determine the order of listing of web sites on search engines. Keywords are normally less sensitive than the title, description meta tag and the content of the web page. The keywords should be a summary of the content of the web page.
 
The "keyword" tag is a list of keywords that you feel are relevant to your site.  The keywords you use should be words and or phrases that are used in search queries for your product or service and also words which you should mention in your actual web page content.