Links are important to the search engines because it shows the engines that other sites think your information is worthy of sharing. Each link is like a vote for your website.
Links are not only good for the engines but good links open up new sources of traffic from relevant, complementary but noncompeting websites.
Linking has gone through so many transformations over the years. First all reciprocal links are good, and then only relevant links are good. Then reciprocal links are not helpful, you need one way links.
