So much pressure that Zuckerberg nervously sat down with CNN to say this:

Now I think what's clear is that in 2016

we were not as on top of the number of issues we should have,

whether it's Russian interference or fake news.

the latest issue?

Facebook admitted that a developer who had accessed the data of 50 million Facebook users

later sold it to a political firm called Cambridge Analytica.

that firm was later hired by the Trump campaign.

Facebook says both parties violated its policies,

but many users feel the company could have done more to protect their data,

and a growing number of people say they're leaving the site.

so, this is 2018.

but to understand what's happening today, you have to look back to

Facebook's policies between 2007 and 2015.

In 2007, Facebook opened its platform to developers,

meaning, it allowed outside apps to access all kinds of user data.

Did you ever play the game FarmVille?

Or did you ever use Tinder or Spotify?

You may have noticed that when you use these apps, they asked you to sign in through Facebook.

Back then, Facebook allowed apps not just to access your information,

but also to access the information of your friends.

And that help the apps and advertisers better understand your preferences.

During this time, Facebook became a fixture in users' lives.

By allowing access to that data, Facebook paved the way for all kinds of apps

to help people find dates, search for jobs, be productive, and stay entertained.

it also ushered in a new style of political campaigning.

The new Obama 2012 smartphone app has everything you need

to get the President's back wherever you go.

And that in turn fuelled the social network's growth.

In 2007, Facebook had 58 million users.

Today, it has more than 2 billion.

But, back to that period we are talking about.

In 2014, Facebook dialled way back on its data sharing policies.

It announced that it would restrict the data that apps could access,

and it would stop allowing developers from getting

the information of your friends without their consent.

Those changes were implemented in 2015.

But this period in Facebook history had already opened the company

up to some of the massive problems it's facing today.

If you pass on that amount of information to somebody who's trying to manipulate you politically

then of course, they're able to exploit your vulnerabilities and send you customized messages

that no one else will see, and no one knows what those messages are.

In 2013, when all of these data was still available,

a Cambridge University researcher accessed the information of 50 million Facebook users.

That data was ultimately sold, against Facebook's policies, to Cambridge Analytica.

Cambridge Analytica says it's launching its own investigation

to determine if the firm engaged in any wrong-doing.

Now Facebook says its investigating all of the apps that had

access to massive amount of user information.

But that's a lot of apps, a lot of Facebook users,

and a lot of their friends.

Well, it's hard to know what we'll find, but we're

going to review thousands of apps.