Let’s suppose you search for a term and find it on page 1 in Google’s listing. In the listing cached pages are indicated. These are pages from the website which Google has loaded on to its own servers. Now over time the position of the website in the listing may change and also the contents of the cached pages may change. Usually Google indexes a site once every month bringing about changes in the cached pages. The Google dance is when a person searches for information and finds a few minutes later the cached pages and possibly the listing position have changed. To the searcher of information it would appear that the update has taken place right then.

The problem is that Google has about 10000 servers located mainly in the US. If a server is indexed with the new information then how can 10,000 servers be updated immediately? Obviously each data center in which the servers are located are updated in a certain sequence. When a search is performed the request for information is sent from data center to center.

The way the searches are performed Google fetches the domain information each time every five minutes or so. This is called the Time To Live. So Google directs its search to a new data center every five minutes. This is when the dance occurs and the indexing seemingly changes. Actually the indexing has not changed it is being accessed from a different data center. It could well happen that you first locate a freshly indexed page and five minutes later an older page. For the observer this also would appear to be a Google dance.

Google has two domains www2.google.com and www3.google.com in which webmasters can view the position of their domains before they are included in www.google.com. These two domains are experimental in nature, if any problems occur in uploading the data it shows up here. Then the original indexed pages may be allowed to remain.

The behavior on www2.google.com and www3.google.com is of special interest to webmasters and Google alike. The results of these are discussed at various forums and Google employees also monitor these discussions.