Crimes against humanity are certain acts which are committed as part of a widespread or systematic attack directed against any civilian population or an identifiable part of a population. The first prosecution for crimes against humanity took place at the Nuremberg Trials. Crimes against humanity have since been prosecuted by other international courts - such as the International Criminal Tribunal for the former Yugoslavia and the International Criminal Court, as well as in domestic prosecutions. The law of crimes against humanity has primarily developed through the evolution of customary international law. Unlike war crimes and genocide, crimes against humanity are not codified in an international convention, although there is currently an international effort to establish such a treaty, led by the Crimes Against Humanity Initiative.
Unlike war crimes, crimes against humanity can be committed during peace or war. They are not isolated or sporadic events, but are part either of a government policy (although the perpetrators need not identify themselves with this policy) or of a wide practice of atrocities tolerated or condoned by a government or a de facto authority. Murder; massacres; dehumanization; extermination; human experimentation; extrajudicial punishments; death squads; forced disappearances; military use of children; kidnappings; unjust imprisonment; slavery; cannibalism, torture; rape; political, racial, or religious persecution that may include the use of blasphemy laws or laws against defamation of religion or other similar wording, or inappropriate hate speech laws; and other inhumane acts may reach the threshold of crimes against humanity if they are part of a widespread or systematic practice.(Wikipedia)