A Google dance is just when the search results change rapidly over a short period of time. It could be the results for just one site - jumping between something like page one and page five - or the results for a set of keywords, or the results across the entire search engine. It usually means that something is about to change - either they're putting a new algorithm in place, or your site is about to be penalised / promoted etc. Google dances usually occur because you're not necessarily always connected to the same Google datacentre every time you search, and changes are usually rolled out slowly across all of the datacentres that Google runs.
Good explanation carl; the best way to avoid this now that you know what it is, is to get a broad range of links (diverse link portfolio). The more you spread the risk, the less volatility you will experience in the Search Engines. More links the better, and the less your rankings should be jumping all over the place.
google dance has 2 different applications. one is when people dance at google party (not kidding...) another meaning, which is commonly known, is the monthly update of google's indexing. usually during such updates, some sites experience temporary fluctuation and the word "dance" is used to refer to that fluctuation
Google updates its servers and listings I would think hourly or daily not just monthly. I have seen changes occur many times within one month.
there are minor updates and major updates across all datacenters so the timeframe would vary for both
Google Dance is nothing but a phrase used to portray major index revise by Google search engine. If you have updated fresh pages and want to know if they have been indexed, glance at Google data centers will provide you an image of your page in future SERP’s.
For new sites there is a 'dance' that affects the site having higher rankings. Sometimes between a PR update or if google is rethinking your positions you will see changes going up and down.
A site fluctuating in serps... ie: one day your on page one the next day page 3 then a few days later on page 5 then back on page 1 again....
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. 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. But the update does not proceed as a switch from one index to another at one point in time. In fact, it takes several days to complete the index update. During this period, the old and the new index alternate on www.google.com. At an early stage, the results from the new index occur sporadically. But later on, they appear more frequently. Google dances.