The reference to this question is Cambridge Analytica's data breach of Facebook, and how come they were able to put out data of 50million users.

I've read a explanation somewhere online stating, can you please explain it more, it is as following:

That platform is free and requires you to provide personal information about yourself. Furthermore, by posting to facebook and interacting with other users, you're providing more data about yourself.

Facebook collects that data and sells it to make money. They use it to target advertisements to you and create a lucrative platform for those advertisers. Part of how they do that is providing a platform that allows third parties to granularly target individual groups of people with particular stories, links, advertisements, etc.

On top of that platform, facebook provides an API for third parties to create apps and games on facebook to interact with users.

Cambridge Analytica used that API to create a "personality test" app on the facebook platform to covertly collect information about users on facebook.

They then used the information they collected to direct campaigns to target particular groups of people with specific information, in an attempt to flood their feeds with stories that would be beneficial to their clients.

As an example: say you're a mildly conservative person but don't necessarily vote in every election.

Cambridge Analytica likely gathered information from you or someone in your social network on facebook that identified you as someone worth targeting. They flooded the feed of your friends who were likely to share stories with fake news stories, tweets, posts, memes, etc that are all designed to get you to get out and vote in an election.

The end goal is to isolate your newsfeed with only stories that Cambridge Analytica's clients want you to see. They want to turn you from a "maybe" voter to a 'I need to vote like my life depends on it" voter. They do this by targeting people they think they need to reach, using data they covertly collecting using the facebook platform and APIs facebook has designed for advertisers but not limited to advertisers.

The controversy is whether or not Facebook knew this was going on, and if they allowed it to happen, when they learned about it, and if they let it go to make money.

And the last major thing what is the role of "christopher wylie" the whistle blower in all this?

And how do I as a newbie programmer understand this in terms of technicalities, I only understand what is API in this.