Facebook's hackathons also focus on another element that Keyani says is important for anyone in the tech industry: speed. "Hackathons are a reminder that if you want to launch something, you can't spend six months to iterate and six more months to develop and test it," he says. "To be on top, you need to make things happen quickly."

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Sixty percent of the projects from the hacks held in December, February and March have already shipped internally or to Facebook users.

"Taking the time to think differently pays off with new ideas and cool things. Hackathons are so valuable because it's a time where we're able to think past the next day or week and just build without constraints," Keyani says. "Instead of worrying if their idea will scale for more than 900 million people, they're able to focus on getting their basic project up and running so the broader team can quickly iterate to make it better."

The events have evolved over the years, and the most recent Facebook hackathon attracted more than 500 employees. Here's a look at how Facebook runs the event, lessons it has learned and tips for how you can adopt the idea at your company.