Keyword Density
Keyword density is a term used in SEO to define the number of times a keyword is used on a webpage compared to the total number of words on that page. Most
In the early days of search engine optimization, webmasters could manipulate a website's rankings by increasing the keyword density. If they wanted to get ranked higher they just added in a lot more popular keywords… over and over if necessary. Some websites really took advantage of this, creating high-ranking keyword-stuffed pages full of nonsense text and irrelevant information. Well, it didn't take long for search engines to ban Keyword Stuffing and change their algorithm so that Keyword density didn't play such a big factor in overall PageRank.
Today keyword density plays only a small part in your PageRank (how high you pop up in search engine results). Many of the more important factors in SEO are relatively hard to manipulate, and in most cases search engines are on the lookout for black hat SEO tactics, such as the Keyword stuffing described earlier. All of the major search engines now penalize for too high keyword density in an effort to combat Keyword stuffing. Today, the trick in search engine optimization is to get the optimum keyword density into your web pages… that magical, elusive proportion of keyword to other text that tells a search engine, "This is good text. Send visitors here."
Most SEO experts recommend a Keyword density of 1% - 3% for best SEO and the highest search engine rankings. This means that for every 100 words, you should have between 1 to 3 keywords.