On-Site-Optimization as well as Off-Site-Optimization both are important and major factors in SEO of a site. But what many webmasters do is concentrate only on Off-Site-Optimization and not on On-Page-Optmization which is totally wrong. As a webmaster, one must strike a proper balance between Off-Site-Optimization and On-Site-Optimization.
On-Site-Optimization (on-page SEO) refers to what can be done on the pages of a website to maximize its performance in the search engines for target keywords related to the on-page content. On-site-optimization factors are the ones that you can control in your site like:- keyword density, text, and links. Off-site-optimization (off-page SEO) is what can be done off the pages of a website to maximise its performance in the search engines for target keywords related to the on-page content and keywords in off-page direct-links.
One of most critical element in On-Site-Optimization is keyword density, and if you can manage to get it right, it you can get a higher rank position for your site. Keyword density is the ratio of the number of occurrences of a particular keyword or phrase to the total number of words in a page. The total number of words does not include only the words in your title, description, or even in the body. But it also includes Title, Meta Description, Meta Keywords, Visible Text, Alt Tags, Comment Tags, Domain Name, Image tags, Linked Text, Option Tags, and Reference Tags.
Keyword density tolerance is not the same for all Search engines. Simply because every search engine’s algorithm differs, and for that you must choose an average keyword density that would make your site rank in the top position in all major search engines. While the exact percentage of keyword density tolerance is still not known, density in the range of 5-7% would be safe for any search engine. It’s up to you, you may choose to optimize your site for just one of search engines, or to target all the major search engines.
You must balance between Off-Site-Optimization and On-Site-Optimization. Also you should give proper attention to keyword density in order to make a site successful.