Keyword density is an indicator of the number of times the selected keyword appears in the web page. However, keywords should not be over used and just sufficient enough to appear at important places. If you repeat your keywords with every other word on every line, search engine will probably recognize your site as spam [...]
Keyword Research is one of the most important part in search engine optimization (SEO) field. In order to drive traffic to your site you need to rank high for keywords that get searched for. It is useless if your site ranks number 1 on search engine for keywords that no one searches for. That is why we need do a research to find those good keywords, keywords with high search demand. You should choose keyword wisely. Choosing keyword is not a guessing game but it is an art.