On-page Optimization is the process of modifying content and certain html tags of your website to focus on the physical web pages & make it more search engine friendly. On-page factors are under your control and can be altered by tweaking the content of your website appropriately. The importance of on-page optimization cannot be stressed enough as it is the basis for search engines to understand the theme and relevance of your website.
This one-time activity is required to make your website search engine friendly. On the entire set of pages on a website, in order to make the content present therein to be more relevant and attractively and neatly displayed, both for the Search Engines spiders to crawl and register them as well as the general visitor to be able to read and navigate through the information relevant to their area of interest.