Facebook CEO Mark Zukerberg has again apologised over a recent data breach at the social media site.
He's testifying before US Senate Judiciary and Commerce Committees over Cambridge Analytica.
Joint Senate Judiciary and Commerce committee Hearing with Facebook CEO, Mark Zuckerberg pic.twitter.com/x3RXVBMsYW
— Senator John Cornyn (@JohnCornyn) April 10, 2018
The scandal has seen the personal details of 87 million users being shared.
Mr Zuckerberg has started two days of questioning by US Senators in Washington after being called to testify.
It's after the British firm Cambridge Analytica got access to data from Facebook users.
Before attending the hearing, Mr Zukerberg posted on his own Facebook page: "I will do everything I can to make Facebook a place where everyone can stay closer with the people they care about, and to make sure it's a positive force in the world."
The social network has been sending messages to those people who have been affected.
In his opening speech, Mr Zuckerberg said the buck stops with him.
"We didn't take a broad enough view of our responsibility and that was a big mistake - and it was my mistake and I'm sorry.
"I started Facebook, I run it and I'm responsible for what happens here".