In 2000, human rights group Amnesty International and African social sciences organization CODESRIA published a handbook for watchdog groups monitoring prisons where torture is suspected. The guide offers insight into just what qualifies as cruel, inhuman and degrading (CID) treatment.

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Amnesty International members protest reported abuses of detainees at the hands of U.S. military at Guantanamo Bay, Cuba, in Paris in January 2007.

The book also mentions the most common forms of torture. The guide cites among the most common torture methods as "beatings, imposition of electric shocks, hanging by the arms or legs," mock executions and forms of sexual assault, especially rape [source: Amnesty International]. While four are physical -- or black torture -- mock executions are white torture (psychological) [source: Ceseraenu]. There is little distinction between black and white forms of torture; both are equally insidious. As the humanitarian group SPIRASI puts it, "Methods of physical and psychological torture are remarkably similar, such that one should not separate their effects from each other" [source: SPIRASI].

What follows are the five most prevalent forms of torture that prisoners throughout the world endure. In the next section, learn about beatings.