Capital punishment, also known as the death penalty, is a state-sanctioned practice of deliberately killing a person as a punishment for an actual or supposed crime, usually following an authorized, rule-governed process to conclude that the person is responsible for violating norms that warrant said punishment. The sentence ordering that an offender is to be punished in such a manner is known as a death sentence, and the act of carrying out the sentence is known as an execution. A prisoner who has been sentenced to death and awaits execution is condemned and is commonly referred to as being "on death row".

Crimes that are punishable by death are known as capital crimes, capital offences, or capital felonies, and vary depending on the jurisdiction, but commonly include serious crimes against the person, such as murder, mass murder, aggravated cases of rape (often including child sexual abuse), terrorism, aircraft hijacking, war crimes, crimes against humanity, and genocide, along with crimes against the state such as attempting to overthrow government, treason, espionage, sedition, and piracy, among other crimes. Also, in some cases, acts of recidivism, aggravated robbery, and kidnapping, in addition to drug trafficking, drug dealing, and drug possession, are capital crimes or enhancements. However, states have also imposed punitive executions, for an expansive range of conduct, for political or religious beliefs and practices, for a status beyond one's control, or without employing any significant due process procedures. Judicial murder is the intentional and premeditated killing of an innocent person by means of capital punishment. For example, the executions following the show trials in Russia during the Great Purge of 1937–1938 were an instrument of political repression.

Etymologically, the term capital (literally "of the head", derived via the Latin capitalis from caput, "head") refers to execution by beheading, but executions are carried out by many methods, including hanging, shooting, lethal injection, stoning, electrocution, and gassing.