What is keyword density? It's basically a measurement of how relevant a given keyword "topic" is to a page of material. For example, this page is quite relevant to the word 'keyword' and the phrase 'keyword density' because both occur many times. More importantly, the ratio of their occurances to the total number of words or phrases on the page is reasonably high because, well, they occur a bunch of times.

That's what keyword density is about. The keyword density of the word "keyword" is calculated by counting the total number of words on the page, then figuring out how many of them are "keyword". Typical highly-ranked sites have at least a 2-3% keyword density for the key search word or search phrase.

But don't take my word for it. Check out the keyword density of your favorite Web page at Search Engine World with their terrific - free - keyword density analyzer. To keep your sanity, I suggest that you set it to ignore words of five letters or less.

Of course, SEOs will tell you that keyword density isn't the only factor to consider when building your page. Among the other important search engine optimization topics are so-called keyword prominence, that is, where on your page the keyword or keywords appear. A title tag is considerably more prominent than the alt text of an image, for example. :-)

Nonetheless, it's quite informative to search for a key phrase that you would like to have match your own site and then use the keyword density analyzer to see the density of top matched pages versus your own. Then add the phrase a few more times on your page, perhaps in the title or a h1 tag or similar, and try again.

And don't be surprised if this change all by itself helps boost your site ranking on the search results.