Like in school, the more friends you have/had, the more popular you are. Well, the same goes for ranking on Google. The more popular you are, the higher you will rank. The heart of popularity on the web is having backlinks pointing back to your site. This shows Google that you are an authority in your industry, therefore you should get higher rankings.
Well, no one...except search engines! If you want people to read your page on the web, you need to have plenty of incoming links pointing right at your site. Search engines value the quantity, quality, and relevance of these links. The trouble with getting "backlinks" to your site, as they are called, is it's kind of difficult. The best way to receive high quality links is by creating a quality page or site. It's one of the most important steps in your SEO campaign!