GitHub – the darling of the software development world that for so many years refused to take a dime of venture capital funding – is taking a serious helping of venture funding: $100 million, to be exact.

The money is coming from Andreessen-Horowitz, the savvy Silicon Valley venture firm started by Netscape founder Marc Andreessen. Andreessen-Horowitz is a prestigious outfit that has a reputation for picking winners such as Skype, Twitter, and Facebook.

It's not exactly surprising that Andreessen-Horowitz would fund a cool company like GitHub. But it's a bit of an eyebrow-raiser that GitHub agreed to take the cash.

The source-code-management-meets-social-network company had intentionally held off on venture funding for the first four years of its life, and that was one of its strengths, co-founder Tom Preston-Werner told us back in January. Not having investors "makes sure that we optimize for customer happiness," he said. "Because if we're not making our customers happy, we have no money. And a big distraction for a lot of startups is that they end up taking a bunch of VC money early and then they lose focus because now they can do anything."

Clearly GitHub didn't make that mistake. The company now boasts 1.7 million software developers.

So why did GitHub take the money? According to Preston-Werner, Andreessen and company had been in discussions with his firm since November. It turns out that the VCs think that software development is becoming more important and disruptive than ever, and they believe that GitHub has an important role to play.

"In the future, we'd love to see companies using GitHub using software internally really collaboratively. We've created this collaborative software creation model that's really special," Preston-Werner says. But that vision will take some money.

GitHub's version-control software keeps track of changes to coding projects, and makes it really easy for coders to discuss and tinker with software that's under development. Open-source projects can use it for free, but companies can also pay big money to host their own private versions of GitHub.

GitHub is a mainstay in the open source community, and companies are paying to use it too, but the money will help push the software into new markets and attract users, says Preston-Werner. GitHub has already developed special easy-to-use Mac and Windows clients, but Preston-Werner would like to develop software specifically for Linux and mobile users too. He'd like to see GitHub used by new types of people – not just coders – but designers and technical authors.

Preston-Werner calls this idea "GitHub Everywhere."

"We want GitHub to work for all kinds of people," he says. And with $100 million in the bank that job could get easier. "You can be much more creative when you're not so focused on the money aspect of things."