In an open letter to parents, caregivers and guardians, U.K. Digital, Culture, Media and Sport Secretary of State Michelle Donelan said protections for children online are at the "heart" of the proposed Online Safety Bill. Under the bill making its way through Parliament, social media companies "will be forced to protect their users, or face billion-pound fines and the potential blocking of their sites in the U.K.," Donelan said. The regulation, she said, is intended to shield younger users from content that is illegal or causes "serious trauma."