Link popularity is a form of "social bookmarking". Thinkabout it, a link is akin to a "vote" from the source. Justlike in the real world, a vote from a source that is knownto be trusted and respected in a specific industry carriesmore weight and contains more social clout, so does a linkfrom a credible online source. Web links are seen as a recommendationor a website endorsement. If the endorsements are from establishedrespected sources in a specific sector, the link is weighedheavier than an unrelated link or links from a source thatis not yet established. s

One way to determine the value of a website is by accessingits PageRank. PageRank is visible in the Google Toolbarand is calculated based on the number of quality incominglinks that a website has. Alexa Rank and TrustRank are alsoindicators of a websites popularity. Alexa tracks the websitesthat people who use the Alexa toolbar visit. Based on thesevisits, they determine the popularity of a website and rankit accordingly. TrustRank is a little more difficult topin down. TrustRank is based on the assumption that goodwebsites rarely link to bad neighborhoods.