Moz defines link building as the process of acquiring hyperlinks from other websites to your own. If you’re new to link building, the basics are simple: a hyperlink (also called a link) is a way for users to navigate between pages on the internet.
When any website, your own, or an external source, links to your content, the link acts like a vote for that page - telling Google, or another search engine, that the page is legitimate and improves its pagerank.
Here is the list: