Google celebrates its 17th birthday. Google celebrate the birthday with an almost worldwide Google Doodle. The Doodle is published in almost every country except a fewparts of South Africa and Asia and the United States of America. In the past Google celebrated the birthday on other dates, too. Since a few years they do it only on 27th of September each year.
After 2 years Google published a new Google Logo. The old fith Google Doodle is replaced by a new one. Google illustrate the new Logo on the Google homepages in several countries e.g. the United States of America or Australia.
The Google is the number 5 sind the start of Google in 1998.
It is an animated Google Doodle. People discuss how long the Google Logo will be and when it will be replaced again.
You can see all Google Logo history in the linked video.