Today, Google celebrates its 21st birthday. This month, in 1998, the company filed for incorporation, the very first step in turning a Stanford dorm room project into what's become Alphabet, one of the world's most valuable companies. Google's revolutionary search engine set its co-founders Larry Page and Sergey Brin up to become two of the richest people in the world, but they never anticipated it would become a multi-billion-dollar company. "When Sergey and I founded Google, we hoped, but did not expect, it would reach its current size and influence," Page wrote to investors in a letter ahead of its initial public offering in 2004. "Our intense and enduring interest was to objectively help people find information efficiently." In celebration of the company's official anniversary, here are eight things you might not know about Google's early days.

Page and Brin 'found each other obnoxious' at first

In 1995, Page visited Stanford for a tour of its campus. He was a prospective student for its doctoral program in computer science when he met Brin, a volunteer guide for first-year students. As Google notes, "By some accounts, they disagreed about nearly everything during that first meeting, but by the following year they struck a partnership." Brin had already wrapped up his first year at Stanford when Page enrolled, and the two stayed in touch. Their newfound friendship was also a test of each other's patience: "Sergey is pretty social; he likes meeting people," Page told Wired in 2005. "I thought he was pretty obnoxious. He had really strong opinions about things, and I guess I did, too." The teasing, Brin went on to explain, was all in good fun: "Obviously we spent a lot of time talking to each other, so there was something there. We had a kind of bantering thing going."

Google started as a PhD project

Despite Google's wild success today, "We didn't start out to do a search engine at all," Page recalled in an interview with the Academy of Achievement. He continued: "In late 1995, I started collecting the links on the Web, because my advisor and I decided that would be a good thing to do. We didn't know exactly what I was going to do with it, but it seemed like no one was really looking at the links on the Web — which pages link to which pages." Page had a particular interest in links back to pages online. The son of a computer science professor, Page understood that links on the Internet could function like citations in the academic world, proving relevance and expertise. Brin and Page combined their knowledge of math and computer science to build an algorithm that took into account the number of links and the importance of those links. The resulting algorithm PageRank, named after Page, would be more efficient than the tools available at the time, such as AltaVista and Excite. Page was adamant on making his doctoral thesis about the web and his research piqued Brin's interest, so the two joined forces. They released the first version of Google on Stanford's website in August 1996.

Google's first iteration was named "BackRub"

Brin and Page's fascination with word play started in 1995, when they launched a project called "BackRub." It was a search engine that stemmed from Page's curiosity with backlinks, or the how one web page links to any other web page (for example, the same way a bibliography "links" one piece of work to many other pieces of work). In 1997, they renamed their search engine Google, "a play on the mathematical expression for the number 1 followed by 100 zeros," the company says, reflecting their mission to organize the world's information.

Page and Brin begged professors for cash

When Page and Brin first came up with the idea for a new and improved search engine, they didn't have the money to access all the computers, disc drives and computer memory they needed, the Stanford Alumni Magazine noted. Professor Hector Garcia-Molina, Page's adviser at the time, said he was "their main bank." The professor helped secure $10,000 from the school's Digital Library budget to help Brin and Page get the parts to build the data servers. Other professors reportedly lent money to Brin and Page as well, with investments as small $40, as the two scrappy students picked up spare parts from wherever they could. Once the two students secured the funds and built their own data servers, they debuted the search engine as google.stanford.edu.

Investing in Google paid off for two professors

The first Google headquarters was in a garage

Similar to Apple and Amazon, Page and Brin used some of their investors' money to open up Google's first headquarters: a garage-turned-office space in Menlo Park, California. The space was part of a house owned by Susan Wojcicki, who later became a Google senior VP and is now the CEO of YouTube. Brin would go on to marry Wojcicki's sister Anne, who would found 23andMe.

The company notes that the old headquarters had clunky desktop computers, a ping pong table and bright blue carpet that "set the scene for those early days and late nights." Google's first server was encased in Lego blocks.

Burning Man inspired Google's first out of office message

The first Google "Doodle" made it to the search engine's homepage in 1998, less than a week before the company incorporated. Page and Brin were off to Nevada to attend Burning Man, the nearly week-long music and arts festival which takes place in the Black Rock Desert. The Doodle featured a stick figure in the logo, which told site visitors that "the entire staff was playing hooky at the Burning Man Festival," Google notes.

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