Keyword density is a search engine optimization term that refers to the number of times a keyword or phrase appears on a web page in relation to the total number of words on that web page.
Keyword density is no longer a significant consideration in search engine optimization; however, if a keyword is repeated too often on a web page then this is referred to as ‘keyword stuffing.’ This Black Hat seo technique was once used to trick the search engines in order to gain a greater relevance score. A web page can be penalized by the search engines for engaging in keyword stuffing.
Search engine optimization today is less concerned with how often the keyword is mentioned than with making sure the keyword or phrase appears in the right spot along with the right content, whether it is a title, heading, paragraph, image or link.