Deacon is the third and lowest degree of the major orders of clergy in the Orthodox Church, following the bishop and the presbyter. The word deacon means server and originally it referred to a person who waited on tables.
With the blessing of the presiding priest or bishop, the deacon leads the people in the collective prayers and reads from the Holy Scriptures during the divine services. He is also responsible for the decorum of the public worship and calls the people to attention at appropriate times.
In addition, the deacon may perform other tasks related to Church life from time to time with the blessing and at the direction of his priest or bishop.
A deacon may be blessed by his bishop and parish priest to distribute the Eucharist to the faithful, either from a second chalice at a regular liturgy where a priest is serving or in connection with a typika service that is celebrated when the priest is absent. In neither case, however, does the deacon consecrate the Holy Gifts. The deacon has no ability or authority to consecrate the Holy Gifts on his own.
Rankings of Deacons
In the degree of their ordination, all deacons are equal. Nevertheless, just as with bishops and presbyters, there are distinctions of administrative rank among deacons. A senior deacon of a cathedral or principal church may be awarded the title protodeacon and claim precedence when serving with other deacons. The chief deacon who is attached to the person of a bishop is called an [archdeacon]. A deacon who is also a monastic is called a hierodeacon.
For formal occasions (for example, in the heading of a letter or when introducing a speaker), one would politely address or refer to a deacon as “The Rev. Deacon [John Smith].