Is “Google Dance” happening now?
"Google Dance" is the term that in the past was used to describe the ups and downs during the period that a major index update of Google search engine gets implemented. The Google database exists on many servers spread throughout the world. A large update of the Google databases can take several days. This happens in case of organic or free listings and not for sponsored or paid listings.
A Google dance is when the Google servers are out of sync with one another. Your web site could be the #2 result for your main keywords on one Google server, and the #9 result on another.
Since August 2003, the famous / infamous Google Dance is no more. Rather, it has become less dramatic. Google now performs updates every week, with most movement occurring on Mondays. These ongoing updates feature mostly minor search algorithm and index updates. Hence, it does happen even now.
There will be minor changes in rankings each month. This is because Google's bot or spider is always running and looking for new updates in the web. It also happens because the bot may have detected that a website no longer exists, and needs to be deleted from the index of Google.
At the time of dance, Google spiders will revisit each website, figure out how many sites link to it, and how many it links out to, and how valuable these links are.
Hence, let us sharpen our Search Engine Optimization efforts on a regular basis to match up with regular updates and changes to Google search algorithm. This will in turn help in mastering over the search results (SERP).