Netflix was a DVD-by-mail business. It’s hard to imagine now that the world’s largest subscription streaming video service keeping television networks on their toes was once a retail business disrupting Blockbuster.

Part of how the company has transformed so rapidly has a lot to do with its revered work culture. There’s a 124-page document that’s now been shared over 13 million times on Slideshare, and was called “the most important document ever to come out of the Valley” by Sheryl Sandberg.

The woman behind “Netflix Culture: Freedom & Responsibility” was the company’s chief talent officer at the time, Patty McCord.

“We [Netflix’s cofounder Reed Hastings and McCord] had been at another company together, and we didn’t like how that company was when we left,” said McCord, who now works as a consultant and advises companies on leadership and culture. “It was like every other company.”

So, the two decided to start a different kind of company. Instead of listing the company’s core values like every other company was doing, McCord decide to write down the things the company valued, what mattered to them, what they expected in their people. For instance, if the company wanted courageous employees, they also wanted employees to know what “courage” looked like and what it didn’t look like.