Hello, I'm Ros Atkins. Each week on the BBC World Service, I look in depth at one of the biggest issues in the news.

Today, I'm going to look at Facebook's power. Now if you can grab your phone and have a look at your

apps. I've got mine here too. I've got Facebook, there's messenger, don't use that too often.

What's app is right where my thumb can reach easily and my neglected Instagram's here too.

All of these apps are owned by Facebook.

Four out of four for me.

If you've got any of them, you're in a group of several billion of us who in some way

contribute to Facebook's enormous power.

The power, for example, to turn off the news.

Making news this morning, social media giant Facebook has followed through on its threat,

restricting people in Australia from viewing news content.

The power to turn off those in power.

Good afternoon and we start with some breaking news.

The President, President Trump has been banned indefinitely from Facebook.

But has Facebook become too powerful?

Well, let's begin with the vision of the man who started it.

It's Chairman Mark Zuckerberg.

Facebook is an idealistic and optimistic company.

For most of our existence, we focused on all the good that connecting people can do.

Idealistic, optimistic, focused on the good.

Keep those words in mind as we consider Facebook's role in three recent stories,

the news band in Australia,

...