Factors that affect the search engine ranking of your site that you can control on your own site through page copy and coding. Example of on-page factors include title tags. Meta data, keyword density of page copy, keyword rich interlinking of site pages and the like. The search engines use on-page factors as part of their algorithms to determine how to rank websites in their index. A well optimized site will address both off-page and on-page factors in hope of ranking well in the algorithmic (organic/natural) results of the search engines.