It is the practice of optimizing individual web pages 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.
On-page optimization refers to improving your website and web page to improve website ranking on the SERP. It involves techniques like image optimization, pagination, meta tags, title tags, content, outbound links, etc.
Optimization of a website and web pages according to SE guidelines, more they are optimized according to the standards easier it for you to rank higher. For instance-
-Meta tags
-Title tagss
-heading tags
-Attractive titles
-Meta descriptions
-user friendly interface
-mobile friendly website
-fast and responsive website
-Content should provide value to the consumer
-URL structure
-Keyword friendly content, etc
on-page optimization refers to factors that have an effect on your Web site or Web page listing in natural search results. These factors are controlled by you or by coding on your page.