Link Popularity and Search Results Rankings

Many webmasters focus on exchanging links (via cross-linking, Webrings, etc) with as many websites as they can. Does this really improve their sites' rankings on search engines?

Why Incoming Links Are Important
Google was the first search engine to come up with the idea of ranking websites. Google assumes that people link to good sites, not bad ones; therefore, a site with lots of incoming links should be ranked highly. This new idea worked so well that soon all of the major search engines began to factor link popularity into their ranking algorithms.

Quality vs. Quantity
In reality, link popularity isn't based simply on the numbers of incoming links a particular site has; who is linking to whom is also important. Incoming links from websites related to the linked site are given more credit in terms of "link popularity." For example, if your site is about computers, a link from a site about software would give you more "credit" in terms of link popularity than a link from a gardening site. (Please note that link popularity and Google's PageRank are different things. Link popularity takes into account a quality factor, whereas PageRank counts only quantity. Google itself does count factor quality into their site ranking system, though, through other means.)

No Quick Fixes
When the idea of link popularity first became public, some people found quick fixes, such as free for all websites and reciprocal links, to increase the number of their incoming links. As you can imagine, one cannot guarantee any quality incoming links from free for all websites. Even reciprocal links are not guaranteed to be deemed "high quality." You might carefully select which sites you exchange links with, but if your link partner has posted your information alongside tens or hundreds of other links, yours would hardly be considered high quality. The bottom line is, forget about these quick fixes. Instead, make your site "link worthy." Once you've done this, other webmasters will link to you without you having to ask them. This is the way to get high quality incoming links, which will in turn improve your search rankings.