Backlinks are incoming links to a website or Web page. In the Search Engine Optimization (SEO), the number of backlinks or inlinks is one indication of the popularity or importance of that website or page. The more quality links and more high PR ranks mean the more traffic and the higher rankings on Google and Yahoo SERPs.
In SEO Process there are three great ways to get links to your website.
Links From Website Directory - You can submit the name (Title), URL, and a brief description of your website to different directories, By this you can back link and also get targeted traffic back from people searching for websites in your topic area!

Links through Articles - By including a link in an article, you can direct readers back to your website. In Internet Marketing during article posting time you can put your site link in the article body or in author bio section of any articles site. You can use internal page’s URL for getting internal link and high traffic to that particular page.
Links from Blog Comment - Commenting on blogs are a great way to get noticed by other users. It helps in increasing visitors to your blogs. If your blog has a unique and good content then visitors will stay to your blog.
Back links are very essential for every site because Google give importance to back links while make a calculation of PR.