Link building refers to actions that increase the number and quality of incoming links to a web page, it also increases search rankings, brings more traffic to your site, and builds site strength.
You can add incoming links
Backlinks are very important for SEO because they help Google realize that your content is credible enough for other people to link to within their website so that it adds tremendous value to your content.
It is more useful when websites with old domains link to your content as the search engine attaches more value to old domains than to new domains. All in all, backlinks enrich your content and add an extra feather that is very useful from an SEO perspective