If your website has many links going to it, you'll get a better ranking in the SERPs since a link going to your site from another is like a vote of confidence. Many website and blog owners write articles for article sites or content farms in order to get more backinks. Many backlinks come naturally or "organically" because someone loves the content on another website or blog so they add a link. Having quality content helps generate organic backlinks which search engines like Google will notice.  Other methods include commenting, paid links, advertising, and link exchanges. Organic links are the best since it means that people consider your content useful or entertaining.