From WhatsApp to PlayStation: how the messaging services differ

Amber Rudd has repeated calls that intelligence services be able to access technology companies, from the American giants to those run from a bedroom

The social media giant became a favourite with extremists in the early years of online radicalisation; it is free, international and allows anyone to sign up and post what they please. Profiles sympathetic to Islamic State and al-Shabaab were once common on the site, but have become less visible since Twitter actively started removing extremist material.