What is the dark web?

The secret club which keeps illegal content hidden, using encryption and anonymisation tools. But can it also be a force for good? The dark web is a hidden part of the internet, giving a cloak to crime. But defenders argue it also keeps activists and whistleblowers safe. Host Claire Graham talks to the BBC technology editor Zoe Kleinman about the origins of the dark web, cyber crime and internet censorship across the world.Presenter: Claire Graham Producer: Cathy Young Researcher: Joe Schultz