If you are planning to enter your pages into search engines (addressed in the next section) so that other people can find them, you will want to add Meta tags to your page. The two most common Meta tags let you specify a description and a set of keywords for the page, respectively, and you can also declare all sorts of other things. Meta tags always appear between the <HEAD> and </HEAD> tags of the HTML source. Here are the Meta tags that appear at the top of the main index page for HowStuffWorks:
<Meta Name="Description" Content="The index to over 50 fantastic 'HowStuffWorks' articles!">
<Meta Name="keywords" Content="how stuff works, how things work, the way things work, information, tutorials, explanation, explains, understand, understanding, tell me, students, teachers, study, educational">
<Meta http-equiv="PICS-Label" content='(PICS-1.1 "http://www.rsac.org/ratingsv01.html" l gen true comment "RSACi North America Server" for "http://www.howstuffworks.com" on "1998.09.23T01:29-0800" r (n 0 s 0 v 0 l 0))'>
The first tag is a description for the page. Search engines use this text directly in their listings. If you don't have a description meta tag, then the search engine either leaves your description blank or uses the first sentence or two from your page.
The second tag indicates a set of extra keywords for the page. Search engines normally index every word on a page, but in many cases you will not use a certain word, in your actual text, that might be used by someone searching for your page. If you know that people frequently misspell a given word, then you might also put the misspelling in the keyword list.
The third tag is an RSAC rating tag. Here is a description of what the RSAC rating system does, taken from the RSAC Web site at www.rsac.org:
"The Recreational Software Advisory Council is an independent, non-profit organization based in Washington, D.C, that empowers the public, especially parents, to make informed decisions about electronic media by means of an open, objective, content advisory system. The RSACi system provides consumers with information about the level of sex, nudity, violence, offensive language (vulgar or hate-motivated) in software games and Web sites. To date, RSACi has been integrated into Microsoft's browser, Internet Explorer and MicroSystem's Cyber Patrol Software. CompuServe (US and Europe) has also committed to rate all its content with the RSACi system."
Some browsers are configured to block pages that are not rated, so by rating your site you avoid problems with those browsers. By rating your site with RSAC you also let people know exactly what kind of content you are providing.
There are a number of other tags you will commonly see if you look at the HTML source of other pages on the Web. Many HTML tools put in tags automatically. For example, here are two tags that Microsoft Word automatically applies to a page if you use Microsoft Word to create HTML:
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=windows-1252">
<META NAME="Generator" CONTENT="Microsoft Word 97">
In all cases, meta tags do not affect the way your page displays in a browser. The description and keywords tags are the most commonly used.