Unction is an archaic word, known in more recent times as "the anointing". It is primarily a Catholic ritual—the last desperate act to save a gravely ill person from death. Unction involves applying oil to the patient's body and pleading for God to spare their life.
Olive oil is the most commonly used oil, but other vegetable oils can also be used.
Anointing the sick is considered one of the seven sacraments by the Catholic church and related sects. Unction is sometimes referred to as the "last rite", and is administered only by a bishop or priest.
The priest or bishop applies oil, sprinkles the holy water and prays to the Holy One to forgive the patient and relieve them of their sins.
Protestant churches usually consider the unction as an ordinance, as opposed to the Catholic church's sacrament. There are some conditions to be met before unction can proceed. The person should be at least seven years of age and should be ready to ask forgiveness for their sins.
Different denominations use different methods of unction. Some apply the oil as a cross only on the forehead and some apply it on seven parts of the body. Unction is usually done in a public church, although it can also be done at home or hospital if needed.