Lynching is an extrajudicial killing by a group. It is most often used to characterize informal public executions by a mob in order to punish an alleged transgressor, punish a convicted transgressor, or intimidate people. It can also be an extreme form of informal group social control, and it is often conducted with the display of a public spectacle for maximum intimidation. Instances of lynchings and similar mob violence can be found in every society.

An extrajudicial killing is the deliberate killing of a person without the lawful authority granted by a judicial proceeding. It typically refers to government authorities, whether lawfully or unlawfully, targeting specific people for death, which in authoritarian regimes often involves political, trade union, dissident, religious and social figures. The term is typically used in situations that imply the human rights of the victims have been violated; deaths caused by legal police actions or legal warfighting on a battlefield are generally not included, even though military and police forces are often used for killings seen by critics as illegitimate. The label "extrajudicial killing" has also been applied to organized, lethal enforcement of extralegal social norms by non-government actors, including lynchings and honor killings.