Meta Tags

Meta Tags are simply statements, visible to Search Engine Robots, but hidden to the human page visitor, about the nature and subject matter of the page.

Title Tag

The Title Element is of key importance. Think of it as a newspaper headline (or two or three), not an essay. Example:

Smith Wins 2011 Florida Vote | Jones Loses Florida Election

A Title Elements first 65 (or thereabouts) characters are displayed as a headline in Search Engine Results Pages.

Description Meta Tag

The Description Meta Tag is important! This tag commonly appears under in the Search Engine Results Pages listing for your website. It's a free ad that you are getting! In Google, as of this writing, you get about 160 characters in the SERPs, although there's evidence Google indexes more characters. Don't waste it with a generic phrase, or omit it and allow the Search Engine to describe you in some other way!

Additionally, the description tag may factor into a Google "Quality Score" and effect the performance of Adwords campaigns.

Google uses Title and Description Tags to help determine if pages are truly unique, according to many SEO professionals. Similar pages may be judged unworthy of inclusion in Search Engine Results Pages and/or crawled infrequently. By using different content in your Description Meta Tags on all of your pages, you encourage Google to crawl and display more of your interior pages.

Keywords

Another Meta Tag that I like to use is "keywords." I know that Search Engines currently put little or no faith in them. However, I feel they are important as a comment to people working on the web page - everyone changing content on the page should be aware of the targeted keywords for that page. Additionally, I tend to believe that future search engine algorithms will use this tag.