Meta tag.

Meta tag is a coding statement in the Hypertext Markup Language (HTML) that describes some aspect of the contents of a Web page. The information that you provide in a metag tag is used by search engines to index a page so that someone searching for the kind of information the page contains will be able to find it. The meta tag is placed near the top of the HTML in a Web page as part of the heading.

This tag will not appear in the site page. It's just a hidden information for crawler and robots to detect what kind of web that created. For the person who are very serious with their web, they must know the function of meta tag. Me myself also did not realised about this at first. But, after I study about the "keyword" for website traffic, later I know the important to study the "the hidden information".

Let's take an example.
Just check out for the good blog/website, and then look at their page source... and we can know their keyword and descriptions via meta tag.
Website-----> Click right -----> Click page source

And by this, later you can submit your url at the search engine incase you want to increase your traffic.
You can read my previous posting about Submit Your Url and don't forget to learn more about Meta Tag.