New Delhi, Sep 27 (IANS): Google celebrated its 21st birthday on Friday with a retro doodle accompanied by a photo of a bulky computer that shows a Google search screen.

The doodle also has a timestamp dating back to September 27, 1998, the day the search giant was established by Stanford PhD students, Larry Page and Sergey Brin.

Initially, the search engine was called "BackRub" and it was later renamed "Google".

In 2001, the company was granted a patent for its technology and the page was listed as its investor.

Google's birthday has changed over the years.

In 2018, the search giant celebrated its birthday on September 26. However, in 2004 and 2003, the date was September 7 and September 8, respectively.

Today the US-based search engine is operating in 100 languages. As of October 2016, it has 70 offices in 40 countries.

Besides, the search giant has created more than 4,000 doodles to date. A team of professionals including designers, illustrators and technicians design these doodles.