SEO (Search Engine Optimization) is part of digital marketing in which ranking of the website is done on specific keywords on SERP (Search Engine Result Page). SEO is free for those who want to do SEO. There are two types of SEO i.e. On-Page SEO and Off-Page SEO.
In SEO, we attract the quality and quantity of traffic organically. On-Page SEO means where you make changes in site and add content so that crawler will crawl the content. In On-Page SEO, publisher adds meta-tile, descriptions so that it would be on SERP. Keywords should be included in the content.
In Off-Page SEO, one can create backlinks so that the website gains little traffic. To Increase PA, DA, ranking of the website in SERP, we create backlinks. There are various parts of off-page submission like social bookmarking, article and blog submission, forum submission, ping submission, image submission, article syndication, infographics submission, blog commenting, etc.