Backlinks are simply clickable links from other sites or pages that linked through your site or your particular link. They also help search engines “find” your site easily.
In general, main concept is not to search out, but give references to other sites. The higher a site or a page has many backlinks, the more probability of being indexed by search engines. Backlinks can create a natural, organic links to your site and are given due relevance to the content or referred to the relevant content.