At this point, we are now leaving all the Hollywood plotlines aside and focus on what Illuminati really is. For starters, the word Illuminati is a designation used all the way from the 15th century to describe a person or a group who claims to be uniquely enlightened. They have this different view among other people about how the society really works, and based on some original writings of the order of the Illuminati, the group appears to be fighting against the oppressive and manipulative machineries that cause hardships for the ordinary citizens of the early centuries. Their trick, though, is to keep their group under the veil and work on their agendas without anyone knowing it.
The only recognized Illuminati group in history is the Bavarian Illuminati, which was founded by Adam Weishaupt in 1776.