(Taken from Wikipedia)

The Industrial Workers of the World (IWW or the Wobblies) is an international union headquartered in Cincinnati, Ohio, USA. At its peak in 1923 the organization claimed some 100,000 members in good standing, and could marshal the support of perhaps 300,000 workers. Its membership declined dramatically after a 1924 split brought on by internal conflict and government repression.

Today it numbers about 2000 members world-wide, but with a recent renewal of organizing activity membership is rising again. IWW membership does not require that one works in a represented workplace, nor does it exclude membership in another labor union.
The IWW contends that all workers should be united within a single union as a class and the wage system abolished. They may be best known for the Wobbly Shop model of workplace democracy, in which workers elect recallable delegates, and other norms of grassroots democracy (self-management) are implemented.