Websites often employ SEO techniques to increase the number of backlinks pointing to their website. Some methods are free for use by everyone whereas some methods, like linkbaiting, require quite a bit of planning and marketing to work. There are also paid techniques to increase the number of backlinks to a target site. For example, private blog networks can be used to purchase backlinks.
While most of the links to your site will be added gradually, as people discover your content through search or other ways and link to it, Google understands that you'd like to let others know about the hard work you've put into your content. Effectively promoting your new content will lead to faster discovery by those who are interested in the same subject. As with most points covered in this document, taking these recommendations to an extreme could actually harm the reputation of your site.
On the other hand, all of the results for the PageRank engine (aside from a single secondary listing) link to the homepage of major American universities. The results are much more logical and useful in nature. If you search for “university,” are you going to want the homepages for popular universities, or random subpages from a sprinkling of colleges all over the world?
The majority of web traffic is driven by the major commercial search engines, Google, Bing, and Yahoo!. Although social media and other types of traffic can generate visits to your website, search engines are the primary method of navigation for most Internet users. This is true whether your site provides content, services, products, information, or just about anything else.