1. The basics
Google's order of results is automatically determined by more than 100 factors, including our PageRank algorithm. Please check out our "Technology Overview" page for more details. Due to the nature of our business and our interest in protecting the integrity of our search results, this is the only information we make available to the public about our ranking system.
2. Why does my page's rank keep changing?
We update our index about once a month. Each time we update our database of web pages, our index invariably shifts: We find new sites, we lose some sites, and sites ranking may change. Your rank naturally will be affected by changes in the ranking of other sites. You can be assured that no one at Google has hand adjusted the results to boost the ranking of a site. Google's order of results is automatically determined by several factors, including our PageRank algorithm. Please check out our "Technology Overview" page for more information on how this works.
You may want to check and see if the number of other sites linking to your URL has changed. This is the single biggest factor in determining what sites are indexed by Google, as we find most pages when our robots crawl the web and jump from page to page via hyperlinks. To find out who links to your site, use Google's link: tool.
3. I'm changing my URL. How can I maintain my rank?
Regrettably, we cannot manually change your listed address at the same time you move to your new site.
That said, there are steps you can take to make sure your transition is a smooth one. Google listings are based in part on our ability to find you from links on other sites. To preserve your rank, you will want to inform others who link to you of your change of address. One way to find out who is linking to you is to try a link search. Enter "link:[your full URL]" into the Google search box. You may not find every page that links to you with this method, but it should help you begin redirecting the links leading to your site. (Please note: we do not serve link queries for all of the sites in our index, so this may not produce any results for your site.) Once your new site is live, you may wish to place a permanent redirect (using a "301" code in HTTP headers) on your old site to inform visitors and search engines that your site has moved.
Finally, if your site goes unlisted for a time, this does not mean you were dropped from our index. Sometimes, in these transitions, we will fail to find a site at its new address. Just be sure that others are linking to you and we should pick you up on our next web crawl.
