Germany is set to start enforcing a law that demands social media sites move quickly to remove hate speech, fake news and illegal material.
Sites that do not remove “obviously illegal” posts could face fines of up to 50m euro (£44.3m).
The law gives the networks 24 hours to act after they have been told about law-breaking material.
Social networks and media sites with more than two million members will fall under the law’s provisions.
Facebook, Twitter and YouTube will be the law’s main focus but it is also likely to be applied to Reddit, Tumblr and Russian social network VK. Other sites such as Vimeo and Flickr could also be caught up in its provisions.