Link Building 101, Part 1 (searchenginewatch.com)
Basically, search engines are saying that if your site is any good, other sites should link to it. If nobody links to your site then it has little relevance. The more links you have, the more "votes" you have on how popular your site it. Thus, the act of link building can be likened to campaigning.
...A page that Google has already rewarded with a decent PageRank (or PR for short) is sometimes called an authority page. Once you have a PR of 1, your site has some power. When your pages achieve a PR of 3, 4, or 5, you have "link juice" to pass on to other pages.
...The allocation of PageRank from one page to another within your site is sometimes called on-site SEO. An advanced form of the discipline is known as "PageRank siloing," or "PageRank sculpting." If you have a Web page with good PR, you can use that page to get other pages higher in the search engine rankings for specific keyword phrases.
...This concept of getting backlinks to a page internally is sometimes overshadowed by trying to acquire backlinks from external pages. Why not use the same concept and apply it to your internal linking structure and reap the rewards?
Getting links to your website is so important. It's also not easy. If it were easy, everyone would be doing it - and if everyone was doing it, then you'd have to be doing it even more to stand out. Right now, it's not too hard to get links. What, Tony? You just said it was not easy. Well, it's not easy but compared to how it's going to be in another 5 years, it's still rather easy right now. So when do you need to get inbound links? Now! Along with that, you need to set up your website to benefit from those incoming links.
There is a lot of linking you can be (and should be) doing on your own website. Pick pages that you want to target for certain keywords - these are called "landing pages" and you need to link those keywords to that landing page. As your website gets more inbound links, it strengthens the PageRank of that page, which makes the internal / on-site links even more important. That's the point. It also guides your website users to the correct place to find what they're looking for - so you can't go wrong setting up landing pages. Benefits galore!
-Tony








