About Link Popularity 

The search engines are fighting a continual war against unscrupulous webmasters who attempt to manipulate the search engine results in such a way that their sites achieve higher prominence than they deserve from their content, known as "spamming". This is a particularly serious problem in the very competitive areas of "adult" and gambling sites. During a recent Alta Vista purge, they discovered a single casino company that had over 20 million pages indexed under many different URL addresses.
   
Obviously, abuse of the search engines in this way will not be tolerated by them, and one of the recent changes seen in their ranking algorithms is that they are attaching a far greater importance to link popularity i.e. the links going to and from your web site. Their thinking is that if a number of sites link to yours then your site must have some worthy content. Furthermore, if the sites linking to yours are also considered important by the search engines, then even more importance is attached to your site.
   
Although the Internet was built on its ability to link to pages on different sites, it has always been a contentious issue on commercial sites as to whether to have external links on the site, since there is always the danger that a surfer will follow a link off of your site never to return. It now seems that on certain very important search engines such as Excite, Google, and to a certain extent Alta Vista, it is impossible to attain good rankings without having links into your site from other sites. These links are almost impossible to get unless you offer a reciprocal link from your site to the other one.
    
A Further problem is that some of the engines are placing such importance on these links that they are using them to determine the subject of your site, thus if you have ten incoming links to your site from Californian Real Estate Sites (your family business !!), but your site is actually trying to alert the world to the danger of Polar Bear extinction, your site will almost certainly be filed under Californian Real Estate !!.
   
If you decide that you want to set up some reciprocal links, it is best to look for sites that are in the same general category as your site, but probably not to link to your nearest competitors. The accepted method of obtaining reciprocal links is to use the search engines to find sites that you would like to link to, and then to send an email to the webmaster of that site, complimenting him on his site, and asking politely if he would like to set up a reciprocal link.