Which search engine was originally called 'BackRub'?

Google was originally called BackRub. Larry Page and Sergey Brin used that nickname for their early Stanford research project because the system analyzed backlinks pointing to web pages.

BackRub began in 1996 as an attempt to understand the web's link structure. Page and Brin reasoned that a link from one page to another could function like a citation in academic writing. Their system used those connections to estimate which pages were important, leading to the development of the PageRank algorithm.

The project was later renamed Google, a name derived from “googol,” the mathematical term for the number 1 followed by 100 zeros. The name suggested the founders' ambition to organize enormous amounts of information. The Google.com domain was registered in 1997, and the company was incorporated in 1998.

BackRub is sometimes confused with a separate search engine because the name sounds like an independent commercial brand. It was actually the early name of Google's own search project. AltaVista, Yahoo, and Bing were different search engines that emerged separately and were never the original name of Google.