The Koch (pronounced "coke") brothers run the second largest privately owned company in the United States, Koch Industries - a business primarily involved in trading, investments and manufacturing. The elder brother is Charles and the younger brother is David.
Charles and David Koch are controversial figures in American society because of their highly scrutinized political involvement. Both are extremely wealthy and staunch conservatives who actively support right-of-center causes and candidates.
They are often demonized on the American left and lionized on the American right. Many on the left see the Koch brothers as representative of all that is wrong with politics and are of the opinion that the brothers' money gives them undue access and influence over governmental power.
Those who support the Kochs argue that monetary political contributions are a constitutionally upheld form of free speech, and that the brothers have as much right to participate in the political process as any other American.