"The best way to get other sites to create high-quality, relevant links to yours is to create unique, relevant content that can naturally gain popularity in the Internet community. Creating good content pays off: Links are usually editorial votes given by choice, and the more useful content you have, the greater the chances someone else will find that content valuable to their readers and link to it."
Search engines were once sequestered to small networks. Today, search engines have evolved to locate relevant content within a much larger library. Anyone who wants to optimize a website for higher rankings needs to understand the science behind Google and other search engines.