The name "Google Dance" is often used to describe the index update
of the Google search engine. Google's index update occurs on average
once per month. The Google Dance is called the time between the start and the end of
an update. Normally the Google Dance took about 4 days. It can be
identified by significant movement in search results and especially by
Google's cache of all indexed pages reflecting the status of Google's
last spidering.
The best time to put new pages online is during the Google-Dance. If
you let too much time lapse between the completion of the update, and
the publication of new content, you may reduce the amount of new
content that will be included in the next update.
During this time, it is possible to see PageRank or the ranking of
a page in the results increasing or decreasing. It is called
Google Dance. You should not panic, you only
should wait approximately 5 or 6 days that all is stabilized.