When the holy Apostles chose deacons, they appointed seven of them because they needed help with the service of the tables, meaning caring for the poor and the social needs of the Church:
"And in those days, when the number of the disciples was multiplied, there arose a murmuring of the Grecians against the Hebrews, because their widows were neglected in the daily ministration. Then the twelve called the multitude of the disciples unto the , and said, It is not reason that we should leave the word of God, and serve tables. Wherefore, brethren, look ye out among you seven men of honest report, full of the Holy Ghost and wisdom, whom we may appoint over this business. But we will give ourselves continually to prayer, and to the ministry of the word. And the saying pleased the whole multitude: and they chose Stephen, a man full of faith and of the Holy Ghost, and Philip, and Prochorus, and Nicanor, and Timon, and
Parmenas, and Nicolas a proselyte of Antioch: Whom they set before the apostles: and when they had prayed, they laid their hands on them." (Acts 6:1-6)
According to the departed Archdeacon Habib Girgis, the former Director of the College of Theology in his book "The Seven Sacrament of the Church": "Deaconia is a rank of priesthood. The person who is charged with it has a special duty to assist the priest during liturgy and the other services of the priest. They are appointed by the laying of hands of the bishop (Acts 6:6) and to them the Apostle Paul made reference in (I Timothy 3:2,8, Philipi 1:1, 2).
Deacon is an Aramic & Hebrew word meaning Servant. And in Greek is pronounced Deacon. One of their duties is to distribute alms to the poor (Acts 6:1-4) and they also can preach with permission from the bishop (Acts 6:5)
When Liturgies were formalized and the services were increased duties were added to deacons as follows:
Apsaltos: meaning singer are to learn the hymnals of the Church and to perform the hymnals in the Church.
Aghnastos: are older and able to read with understanding, so they can participate in the readings.
Sub-deacons: is a rank that is achieved after one is recognized in the previous two ranks. The Sub-deacon is appointed to this rank by cutting four tufts of hair from his head on the sign of the cross, a sign of dedication to the service of God.
Deacon: A person who completed the previous three ranks can be elevated to the rank of deacon by recommendation from the priest to the bishop. The deacon is appointed to this rank by the laying of hands of the bishop. A full deacon is usually an adult male who has been in the service of the Church for
a long time, and has been recognized as a dedicated servant. A deacon can assist the priest in serving communion according to the Cannons of the Church. A deacon according to the Cannons can carry the cup during communion, meaning serve the blood.
Archdeacon: When the Holy Apostles choose 7 deacons, the appointed Stephen as a head of the deacons (archdeacon). There should be no more than one archdeacon in a congregation (Church). An archdeacon is a person who is really interested and seen by the bishop as qualified for the priesthood.