Onpage optimization (AKA on-page SEO) refers to all measures that can be taken directly within the website in order to improve its position in the search rankings. Examples of this include measures to optimize the content or improve the meta description and title tags. Conversely, off-page SEO refers to links and other signals.
See also Searchmetrics Content Optimization.
Learn now to optimize your on-page content and page elements to rank for Universal and Extended Search elements. Download the free whitepaper and guide from Searchmetrics.