SEOers often put a lot of stress on Google’s PageRank number. PageRank is a general measure of the number of links to a site. The idea is that a site with more links to it is more important and deserves a higher ranking in the search engine results pages. To be more precise, a site with more paths to it is considered more important, where a path is a number of pages linked together. This means a link from a site that has a higher PageRank (more paths to it), is of more importance than a link from a site with a lower PageRank. Google is not the only search engine that uses PageRank, Yahoo! and other engines also factor something similar to PageRank into their algorithms.
Most sites that are candidates for back links won’t funnel significant traffic to a site. They exist to link to other sites, so that pages can get ranked in the search engines. Other sites might be looking for content to draw people to AdSense ads. Links are a commodity. Sites will often link to whomever no matter what the content, as long as it won’t get them penalized and the price is right. The fundamental flaw in Google’s (and other engines) assumption is that sites won’t link to other sites that don’t have good content. Sites will link to any other site that will pay them or will get them higher rankings, barring penalties. Commercial sites usually don’t get traffic because of quality content; they get traffic because they are listed well in the search engines. This is a generalization, but it seems to be true.
This is why Google and other search engines have to consider other criteria when ranking sites. Getting a higher PageRank for the sake of seeing a higher number in your toolbar is pointless, and might even harm your site’s rankings (Most likely, Google knows that a domain with six pages of content doesn’t deserve a PageRank of 8, and will act accordingly). It’s more important to have high quality links (or links that appear to have a high quality). This means focusing on links that are from sites with a similar topic and are not generic.
PageRank is not a useless number. For two non-generic sites that both are on a related topic, I would choose to get a link from a site that will put a link on a page with a higher PageRank number. All other factors equal, I would also choose to get a link on a page that has PR3 and two other links on the page, instead of a page that has PR4 and 200 other links on the page. I would not waste time getting links from a large number of independent peers (unrelated documents) or free for all sites because it will increase my PageRank.
When an SEO company gets your site a higher PageRank, it really doesn’t mean much unless the links are from sites that Google considers authoritative in the topic of your site.
