Founded in 2009 and led by former Facebook executive Adam D'Angelo, Quora has seen what happens to content sites that count on Google's search engine for traffic. All too often, a sudden tweak to Google's algorithm can drop a site's search ranking and leave the webmaster scrambling to fix the problem.
A primary source of Quora's traffic is organic, meaning people are coming directly to Quora.com to ask questions and provide answers to those posed by others, said Marc Bodnick, who runs business, marketing and community at Mountain View, California-based Quora. Beyond that, the site attracts users from a variety of places, including Google, Facebook, Twitter, Microsoft Bing and LinkedIn.
"You don't get loyalty from an algorithm," Bodnick said in an interview. "When you're totally dependent on a single channel, it means people don't really like your product."
Google's algorithms, designed to lift the presence of sites deemed high quality, have outsized influence over the flow of Internet traffic, because the company, also based in Mountain View, controls over two-thirds of the U.S. search market.
CNBC.com has reported on small businesses that have seen their traffic and revenue slashed overnight after a Google update, with almost no ability to recover. Content sites that Google has viewed, fairly or not, as spammy, like those from Demand Media, Mahalo and HubPages, have been particularly hard hit by past algorithm changes.
Quora, whose stated mission is "to share and grow the world's knowledge," lets users ask questions on the topic of their choice. The library spans 500,000 subjects, and popular fields include technology, economics and personal health.
Quora likes traffic that comes from anywhere, but the company wants to get as many consumers as possible coming to its website and mobile apps to find answers, rather than just typing questions into Google.
"You want people to just enjoy using your product," said Bodnick, who previously co-founded investment firm Elevation Partners, along with U2's Bono, Roger McNamee and others.
Coincidentally, some people even turn to Quora to figure out how to improve their Google rankings. A private tutor posted the question, "Why does my website rank so poorly in Google search results?" The questioner included a link to the site so experts could help find the problem. Respondents chimed in with comments like, "make site engaging and update it regularly."
Google recommends that sites aim for diversified traffic sources. In an October 2013 post on Search Engine Watch, Google's webspam head Matt Cutts is quoted as telling webmasters to have "eggs in lots of different baskets."
"You should always have a very well-rounded portfolio of ways to get leads, whether from people walking through your door or Yellow Pages or whatever it is, because you can't count on any one channel always working out perfectly," Cutts, who's currently on leave from Google, told Search Engine Watch.
A Google spokesman declined to comment beyond the company's past statements.
While Quora has continued to build its user base, the company has yet to start generating revenue.
The 100-person company has raised $161 million in venture funding, with more than half coming in April at a valuation of around $900 million. That's a healthy dose of optimism for a start-up without a working business model.
Bodnick said Quora will likely start experimenting later this year with selling ads related to a person's searches and interests. By way of comparison, he uses TripAdvisor as an example of a company that's built a $10 billion business by showing ads that are relevant to travel inquiries.
"We know you're looking for something," Bodnick said. "We'll serve you ads against that knowledge."
--Clarification: This story has been updated to more accurately state the sources of Quora's traffic.