Links from other sites are the life line for any website. Links from other sites significantly determine your website page rankings for different keywords and your website PR as well.

Many people tend to get links from high PR websites like directories etc. Used to be the case when getting links from high PR site paid off really well. Not any more.

With current search algorithm getting links from related sites is the most important. No matter what PR the linking site has, if its related to your website you should consider getting a link from it. And that makes the game of link building difficult.