The Google Dance
The Google dance is the term used to describe the index update of the Google search engine. This indexing usually happens around once a month, although some SEOs insist this Google Dance happens continuously. Whilst the Google dance is in process you will notice changes in your rankings, and after the “dance” has finished you will be able to see ranking/position changes and improvement in Google PageRank (that is if you have made any improvements to your site).
The Google Dance is rumoured to happen during the last third of each month, although this is speculations rather than fact.
Google has two other servers apart from www.google.com these are www2.google.com and www3.google.com. Most of the time the results are the same on all three servers, except from when the Google Dance occurs. The rankings that can be see on www2 and www3 is thought to be the new rankings, which will transfer to www once the “dance” is over.
Below is a Google Dance tool from SEOchat, which will show you the results for all three Google servers:
Google Dance Tool