But before you think you need a 10 to be considered important, consider this: of the billions of sites on the web, only a handful-literally-have a PageRank 10. Google is one. Yahoo is another. Even some of the most visited sites like AOL, EBay and Amazon aren't perfect. They have a 9. While the popular social networking sites like MySpace and YouTube are ranked 8.

Those are among the elite sites that drive millions of visitors to their sites each day. A more standard quality PageRank is anything between 4 and 7. You want your site to be at least a four, and you only want to link to sites with a four or higher.

If you're just starting out, you may only have a rank of 0. This could mean that a Google spider hasn't crawled your site yet, you have no or few links to your site or you violate the search engine guidelines at Google. To increase your visibility in the search engines, you need to increase the number of quality sites that link to you.

Google sees each link to you as a vote for your page. The more votes you have, the more valuable Google considers your site. But if you vote for people more often than they vote for you (which means you have more outbound links than inbound links), your value begins to decrease.

And the number of votes isn't the only thing that Google considers. The rank of the page casting the vote is even more important. If site A, a PageRank 7, votes for you by linking to your site, that vote is weighed more heavily than a vote from site B with a PageRank 1. The 7 helps increase the importance of your page; the 1 detracts from it.

Only it's not quite that simple. Content also counts in the linking game. If that 7 site links to you but has content related to sports when your content is related to knitting, that vote does nothing to help your PageRank. Google has text-matching techniques to find pages that are relevant and important to rank the weight of your links.

Having links to your site on other sites in your niche is therefore important, but if you are just getting started, be sure all of your pages are linked back to your home page. By doing so, you are beginning to take steps toward increasing your PageRank and consequently increasing your visibility in the search engines.