There are two parts of SEO Onsite (On-page Optimization) and offsite SEO(Off-page SEO). Onsite SEO refers to optimizing your website pages or blog for a particular keyword that is called on-page SEO optimization. it includes all aspects of optimization from keyword research to technical SEO.
When you all done on-page SEO then another step comes in off-page SEO which is done outside our website this process also called backlink creation or backlink building. It includes so many steps like social bookmarking, question and answer, article submission and profile creation, etc.
By following both of these steps you can rank your website higher on google, this is also called SEO.