The following is a simple explanation of what web page keyword density means:
Keyword density is
a ratio/percentage based measure indicating
the frequency of a chosen keyword
within a web page in relation to the total
word count, and/or by comparing the keyword's frequency to the frequency of other keywords appearing in the web page. Keyword density
can be broken down and analyzed at two main levels:
entire website or on individual web pages. Keyword density is a factor
used by search engine algorithms in order to determine the
relevance of a web page. This is one factor that influences how search engines generate ordinal ranking within search query results. Some of the areas that are measured into the total density include the web page copy, the HTML Title, and META description.
The keyword density cloud of this web page was created by Wordle.net
How do I check my web page keyword density?
There are some really good free tools out there for checking your web pages.
Google's Webmaster Tools
Google's Webmaster Tools is free and provides a feature that shows a listing of your site's most common keywords. Google will crawl your site to generate this list.
Keyword Density Checker
This tool shows a keyword cloud which is a visual depiction of keywords most frequently used indicated as bold or larger font size.
Centro Keyword Density
Interesting tool that seems to show more keyword phrases. It also includes the cloud, count, and percentages.
Wordle FUN Word Clouds
Wordle is a toy for generating “word clouds” from text. Greater prominence is given to words that appear more frequently in the source text.