A more thorough explanation:

Definition: Black Hand is a term used to refer to several secret societies that were active in the late 19th and early 20th centuries. These organizations were mostly composed of anarchists or separatists and engaged in terrorism.

One example of the Black Hand was a Sicilian-Italian criminal organization that extorted money from Italian immigrants in the United States through threats and acts of violence. This organization had chapters throughout the United States and Canada, and the New York City Police Department even created the nation's first bomb squad to deal with the bombs used by the Black Hand.

Other examples of the Black Hand include a band of Spanish anarchists in the late 19th century and a group of Serbian anarchists in the early 20th century. These organizations were not related to each other or to the Sicilian-Italian Black Hand.

These examples illustrate how the Black Hand was a term used to describe various secret societies that engaged in terrorism and other illegal activities. The Sicilian-Italian Black Hand, in particular, was known for its extortion of Italian immigrants in the United States, which led to the creation of the first bomb squad in the country.