Murder is the act of intentionally causing the death of another human being. It is considered a crime in most jurisdictions, often subject to harsh punishments.
The definition of what constitutes murder in English law was given by Sir Edward Coke, a jurist from the 17th century. In his Institutes of the Lawes of England, Coke describes murder as:
[…] when a man of sound memory and of the age of discretion, unlawfully killeth within any county of the realm any reasonable creature in rerum natura under the King’s peace, with malice aforthought, either expressed by the party or implied by law, so as the party wounded, or hurt, etc. die of the wound or hurt, etc. within a year and a day of the same.Coke, Institutes of the Lawes of England
The ‘year and a day’ rule was repealed by the Law Reform (Year and a Day Rule) Act 1996.