Liz Gannes explains that 40% of Quora's traffic is on mobile, and that the main thing they're going to do with this money is sit on it:

The company, which is led by early Facebook CTO Adam D’Angelo, has now raised an $80 million Series C round led by Tiger Global Management and including previous investors Benchmark, Matrix Partners, North Bridge Venture Partners and Peter Thiel.

Sources familiar with the situation said the round values Quora at about $900 million.

Based in Mountain View, Calif., Quora has 70 employees and had previously raised about $60 million.

“Most of the money is just going to sit in our bank and be insurance for us, in case there’s some sort of financial crisis, or anything unusual that might happen,” D’Angelo told Re/code. “It’s really important that we’re building a product and service that can last and stay independent forever.”

The Quora IPO is not happening anytime soon, because the company has no revenue. “We will have to go public or have other investors that will buy them out,” D’Angelo said. “We’ve selected for investors that are very long-term focused.”

Quora doesn’t disclose its own size, traffic-wise. It never has. ComScore says the site had 2.2 million U.S. visitors from Web and mobile in February 2014. Though its content may be clearly much lower quality, Yahoo Answers is way bigger, with 93.9 million visitors in the same period.

Quora’s business and marketing head Marc Bodnick, formerly co-founder of Elevation Partners, claimed public measurement services systematically undercount Quora traffic by five to 15 times. He called growth “steady, continuous and strong,” but, of course, declined to pin it down to a number.

Quora’s next big project is internationalizing its service, which already gets 40 percent of usage from mobile. In all likeliness, that should lead to a growth spurt, as the site currently only supports English content.

D’Angelo also said the site would likely introduce its first ads next year.

Other ways the company will make its gigantic bank balance go down will be by building better tools for users to explore their own Quora writing history.

But some of Quora’s costs are actually decreasing — at least for a moment. The recent cloud hosting wars between Google, Amazon and Microsoft ended up bringing Quora’s Amazon EC2 hosting fees down about 30 percent, D’Angelo said.

“We think we have the best Q&A on the Internet, the biggest library of first-hand knowledge on the Internet, and the second-biggest library of general knowledge after Wikipedia,” Bodnick said. “Our goal is to put the money in the bank as insurance against the future, and keep building the permanent library, and make sure it lasts forever and ever.”

I like the line that Quora is "the second-biggest library of general knowledge after Wikipedia."

I guess this means that Wikipedia is worth more than $1 billion?

I'm also unclear on what Quora lasting forever means, but perhaps that is because I've been watching Neil deGrasse Tyson's Cosmos lately.