Unction is an oil ritually applied to sacred statues and the dead for magical and religious purposes.
The practice was common in ancient Egypt, Mesopotamia and among the Hittites. The Jews of the Old Testament and the first Christians also used oil for anointing.
The Catholic sacrament of Holy Unction or anointing of the sick replaced Extreme Unction in 1972.
The old name: “Extreme Unction” means last anointing. “Extreme” was used to mean “last.” “Unction” means anointing. The sacrament has not changed, but the name “Sacrament of the Sick” or “Anointing of the Sick” better conveys that fact that it is a healing sacrament that is meant for the living as well as for those near death. It has always been meant for both. This is not new. The sacrament has not changed–just the name.
Fr. Vincent Serpa, O.P.¹
This sacrament also appears within the Eastern Orthodox Church. For Catholics, to participate in the sacrament one must
(a) be of the age or reason
(b) have recently received the sacrament of Penance and Reconciliation, formerly called Confession
In actual practice, however, there is no real way for a priest to definitively determine if a parishioner has recently received the sacrament of Reconciliation or not. And I suggest elsewhere, Catholic teaching compared to what parishioners actually believe and practice might not always be in accord. ²
¹ “What ever happened to Extreme Unction?” » http://forums.catholic.com/showthread.php?t=28380