At this point, almost everyone knows about Anonymous, a group of hacker activists. Their moto is working on ideas rather than directives. They are known for their many distributed denial-of-service attacks on governments around the world, but also on religious and corporate websites.
The group originated in 2003, and started first on the imageboard 4chan. The concept began as a group of many online and offline users simultaneously existing as an anarchic and digitalized global brain.
Since their beginning in the early 2000s, Anonymous has become popular and influential group. They have risen to the occasion so many times. And because of their activity, many users have been arrested for involvement in these cyber-attacks. Countries like the United Kingdom, the Netherlands, United States of America, Turkey, Spain, and India have arrested members of the group.
They can easily be recognized by wearing the Guy Fawkes masks from the movie V for Vendetta. The movie has the same idea, an anarchist revolutionary battles a totalitarian government.