I found out a few things on them and I included hyperlinks to the source of this information. You can find more on the internet.
The Illuminati was a secret society in Bavaria in the late 18th century. They had a political agenda that included republicanism and abolition of monarchies, which they tried to institute by means of subterfuge, secrecy, and conspiracy, including the infiltration of other organizations. They fancied themselves to be "enlightened" but they had little success and were destroyed within fifteen years of their origin (Pipes 1997).
Paranoid conspiracy theorists (PCTs) believe the Illuminati cabal still exists, either in its original form or as a paradigm for later cabals. Many PCTs believe "that large Jewish banking families have been orchestrating various political revolutions and machinations throughout Europe and America since the late eighteenth century, with the ultimate aim of bringing about a satanic New World Order." (The Skeptics Dictionary)
The Illuminati (plural of Latin illuminatus, "enlightened" ) is a name given to several groups, both real (historical) and fictitious. Historically the name refers to the Bavarian Illuminati, an Enlightenment-era secret society founded on May 1, 1776. In more modern contexts the name refers to a purported conspiratorial organization which is alleged to mastermind events and control world affairs through governments and corporations to establish a New World Order. In this context the Illuminati are usually represented as a modern version or continuation of the Bavarian Illuminati. (Wikipedia)