SEO is a process of using several online marketing techniques to gain good keyword ranking on the SERP.
There lots of advantages of SEO such as:
Organic traffic.
Brand promotion.
Keyword ranking.
Website authority improvement.
If you are trying to get keyword ranking and traffic towards your website by building backlink, I suggest you to must focus on high domain authority sites to give preferance in backling creation. High authority backlinks are very useful for your website ranking.