Anonymous is a decentralized international activist/hacktivist collective/movement that is widely known for its various cyber attacks against several governments, government institutions and government agencies, corporations. And the Church of Scientology.
It originated in 2003 on the imageboard 4chan representing the concept of many online and offline community users simultaneously existing as an anarchic. Digitized global brain.
Anonymous members (known as Anons) can be distinguished in public by the wearing of Guy Fawkes masks in the style portrayed in the graphic novel and film V for Vendetta.
However, this may not always be the case as some of the collective prefer to instead cover their face without using the well-known mask as a disguise. Some anons also opt to mask their voices through voice changers or text-to-speech programs.