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BackRub: Google's First Name

Zusammenfassung

Larry Page and Sergey Brin named their search engine “BackRub” in 1996 — a reference to its core algorithm: analyzing back-links (links pointing to a page) to determine that page’s importance. The name was changed to “Google” in 1997, a misspelling of “googol” (the number 10^100), chosen to suggest the vast scale of information the search engine intended to index. The name change happened partly because an investor wrote a check to “Google” — misspelling the intended “Googol” — before the company was formally incorporated, and the founders kept it.

BackRub and the PageRank Insight

In 1996, Larry Page was a Stanford PhD student looking for a dissertation topic. He became interested in the mathematical structure of the World Wide Web — specifically, which pages linked to which other pages. His supervisor Terry Winograd suggested that understanding the link structure might be academically interesting; Page began downloading the web’s link graph and analyzing it.

The core insight was this: a link from Page A to Page B is a vote for Page B’s importance. More links = more important. But not all votes are equal: a link from a highly-linked page is worth more than a link from a page nobody links to. This recursive definition — a page’s importance depends on the importance of pages that link to it — could be solved as an eigenvector problem on the web’s link matrix.

Sergey Brin, also a Stanford PhD student, joined the project. They named the crawl “BackRub” because it analyzed back-links — links pointing back at a given page. The BackRub crawler ran on the Stanford servers from 1996 to 1997, growing until it was consuming so much bandwidth that the university asked them to stop.

The PageRank Algorithm

When they converted BackRub into a search engine, they renamed the core ranking algorithm PageRank — simultaneously a reference to its inventor Larry Page and to the concept of ranking web pages. The algorithm’s mathematical formulation:

PR(A) = (1-d) + d × Σ (PR(T_i) / C(T_i))

where d is a damping factor (typically 0.85), T_i are pages linking to A, and C(T_i) is the number of links on page T_i.

This formulation made Google’s results dramatically better than the keyword-frequency approaches used by AltaVista, Lycos, and Excite. Those engines ranked pages by how often the search term appeared; PageRank ranked by link-based authority, which was much harder to game and much better correlated with actual usefulness. The full competitive story is covered in The Search Engine Wars.

The Name Change and the Check

In 1997, Page and Brin registered the domain “google.stanford.edu” and began referring to the project as Google. The intended name had been “Googol” — the mathematical term for 10^100, suggesting the enormous quantity of information to be indexed — but the domain googol.com was already taken.

The specific story of the check: in August 1998, Sun Microsystems co-founder Andy Bechtolsheim — described in Andy Bechtolsheim and Sun — met Page and Brin for a brief demo in the parking lot of a colleague’s house at Stanford. He was impressed enough to write a check on the spot for $100,000. The check was made out to “Google Inc.” — not “Googol Inc.” — either because Bechtolsheim was already aware of the spelling they were using, or because he misspelled it and they decided to incorporate under that spelling. The precise sequence is disputed in various accounts. What is certain is that Google was incorporated in September 1998 with the “Google” spelling established before incorporation. Bechtolsheim’s check couldn’t be cashed until the company existed; it sat in a desk drawer for weeks.

The Scale of What the Name Implied

“Googol” — 10^100 — is a number so large it has no physical meaning. There are approximately 10^80 atoms in the observable universe. A googol of anything would exceed the total count of any material object. Choosing a word meaning “incomprehensibly large number” as the name for a search engine was either audaciously accurate (the web is indeed enormous) or hubristic (claiming they would index all of it). As described in Google: The Company, both turned out to be true.

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