On-page SEO is the practice of optimizing individual web pages in order to rank higher and earn more relevant traffic in search engines. On-page refers to both the content and HTML source code of a page that can be optimized, as opposed to off-page SEO which refers to links and other external signals.
For those new to on-page SEO, we highly recommend reading our On-Page Ranking Factors. On-page SEO has changed over the years, so it's important to keep up with the latest practices. Below is the latest post about on-page SEO from the Moz Blog, and we have chosen our favorite resources to help you along your journey.