Google was originally called BackRub.
The domain Google.com was registered on September 15, 1997.
But before that, founders Larry Page and Sergey Brin had another name for their search engine: they called it BackRub.
Page rank is the most complicated part of the method.
It works by ranking pages based on valid backlinks on the website.
That is why it was initially named Backrub by the inventors of it.