Before Google was the monolithic search engine we know today, it was called BackRub.
You may ask yourself why anyone would choose such an unmarketable name, but there was a (somewhat) practical reason. As previously reported by Business Insider, an early version of the search engine analyzed websites' back links to see how high up on search results they should be placed.
"Google" came from a fellow Stanford student, who suggested "Googolplex," which is the name for 10 to the power of "googol." (A "googol" is 10100, written as 1 followed by 100 zeroes.) Eventually, the name was reconfigured to "Googol," then finally to its current form, apparently thanks to a simple spelling error. Co-founders Larry Page and Sergey Brin registered the new domain name on September 15, 1997, and the rest is history.