Facebook has insisted that it has never sold user data — but one of the revelations from the documents is that the company discussed the possibility of charging for access to it.
In one October 2012 email, Zuckerberg discussed a potential monetization model that would let developers use Facebook's login tools or publish to Facebook for free, but would charge for "reading" data.
How much did he value his users at? Around $0.10 each, per year.
"A basic model could be: Login with Facebook is always free ... Pushing content to Facebook is always free ... Reading anything, including friends, costs a lot of money. Perhaps on the order of $0.10/user each year," he wrote.
In its response, Facebook said: "We explored multiple ways to build a sustainable business with developers who were building apps that were useful to people. But instead of requiring developers to buy advertising – the option discussed in these cherrypicked emails – we ultimately settled on a model where developers did not need to purchase advertising to access APIs and we continued to provide the developer platform for free."