If you read back through older information on search engine optimization (SEO), such as information from 4-5 years ago, you will likely notice that keyword density played a crucial role in how a page ranked in the search engines. In case you are unfamiliar with the term, "keyword density" refers to the ratio of your target keywords to the rest of the words on a webpage. For example, a keyword density of 5% meant that 5% of all the words on a given page were your target keywords for that page.
Webmasters and SEO's (myself included) would spend a great deal of time analyzing pages trying to determine the perfect keyword density that would send our pages to the top of the search engines. Each engine had their "sweet spot" when it came to keyword density. If you could find that sweet spot, you were golden.
Unfortunately, those days are gone. So much of a pages ranking today is determined by FAR more than keyword density. Factors such as link popularity, link reputation, LSI (latent semantic indexing), supporting phrases, etc. all player a role in one way or another and to one extent or another in the ranking of a page. There are so many other elements in play that it is not uncommon for pages to rank quite high for a term that is not even on the page given the right mix of other factors.
So, does this mean keyword density is dead? Well, to some extent yes. Keyword density still plays a part in how a page ranks, it is simply that it is nowhere near as important a part as it was 4-5 years ago. In other words, if all other things are equal, the page that has the keyword on it, will outrank a page that doesn't, but just because a page has a high keyword density does not mean it is going to rank well in the engines.
When designing pages with seo in mind today, I generally shoot for a keyword density anywhere from 3-15%. The density will generally depend on the amount of text on a page. I don't' sweat it. I want the page to read naturally. I also make an effort to include other "supporting" phrases in the page such as synonyms and other words or phrases you would expect to find on a page with the keyword I am targeting. This is becoming more and more important, but I'll cover that more in another article.
See you at the top!
SEO: No Perfect World