keyword density is the ratio of the word that is being searched for, i.e. the keyword, against the total number of words appearing on a given web page. If your keyword occurs only once or twice in a page of 500 or more words, obviously it has a lower keyword density than a keyword that would occur six or seven times in a page of similar length.

The keyword density tool is useful for helping webmasters/SEO's achieve their optimum keyword density for a set of key terms/keywords.

As far as search engines are concerned, if a particular keyword has a higher density on that particular web page, then the chances of that page obtaining a much better search engine ranking increases almost exponentially.

Keyword density is important since search engines use this information to categorize a site's theme, and to determine which terms this site is relevant to -- the perfect keyword density will help archive higher search engine positions. Keyword density needs to be balanced correctly (too low and you will not get the optimum benefit, too high and your page might get flagged for 'keyword-spamming').

Keyword's should be chosen with care and you should use those keywords as often as you can ,and still "read" well. The amount of times your keyword comes up in your copy compared to other words is called keyword density.

Depending on who you ask, what search engine you are dealing with, or the phase of the moon, you will get a different answer from every SEO expert on what the right density should be.

Don't try and "trick" the search engines. You almost always loose out in the end. Real content, written for real content usually ends up outranking sites that try and cheat the search engines.

Decide right now to play by the rules and when your competition begins to get banned, you will be up and running.

Improving the keyword density on your website is one of the fastest and simplest ways to increase your site's visibility in the search engine results pages.