How do PageRank updates work?

How do PageRank updates work?

 

 

Google updates Toolbar Pagerank every 3 or so months:

  • 4 February 2013
  • 7 November 2012
  • 2 August 2012
  • 2 May 2012
  • 7 February 2012
  • 7 November 2011
  • 1st Week August 2011
  • JULY 2011
  • JUNE 2011
  • JANUARY 2011
  • April 2010
  • Dec 31, 2009
  • 30 October 2009
  • 27/28 May 2009
  • June 2009
  • 1 / 2 April 2009
  • 30-31 December 2008
  • 27 September 2008
  • 26 July 2008
  • 29 April 2008
  • 9 January 2008
  • 26 October 2007
  • 28 April 2007