"Deacons share in Christ's mission and grace in a special way. The sacrament of Holy Orders marks them with an imprint (“character”) which cannot be removed and which configures them to Christ, who made himself the “deacon” or servant of all. Among other tasks, it is the task of deacons to assist the bishop and priests in the celebration of the divine mysteries, above all the Eucharist, in the distribution of Holy Communion, in assisting at and blessing marriages, in the proclamation of the Gospel and preaching, in presiding over funerals, and in dedicating themselves to the various ministries of charity. "

(1570 Catechism of the Catholic Church)

Ministry of Charity

A deacon is ordained by the local bishop for service to the diocesan -- local -- Church. In communion with the bishop and priests, deacons are ordained for service, which is indicated by their title, which is translated from the Greek word diakonia "to serve." Ministries of service may be in the parish, diocese or other areas of need in the secular world, such as hospitals, prisons, homeless shelters, and food pantries. Deacons engage in ministry to and with a variety of people.

Ministry of the Word

As the ordinary minister of the Word, the deacon’s role includes the proclamation of the Gospel during liturgy and the Easter Proclamation (Exsultet) at the Easter Vigil. In addition, the deacon preaches (usually based on a schedule). Other ministries of the Word may include catechetical instruction, teaching, and sacramental preparation. 

Liturgical and Sacramental Ministries

The deacon may administer the Sacrament of Baptism, witness the Sacrament of Marriages and presides liturgies such as Communion Services, Eucharistic Adoration and Benediction, Liturgy of the Hours, and funeral and burial services. During the Mass, in addition to proclaiming the Gospel and preaching, the deacon carries the Book of the Gospel in procession and is the Ordinary Minister of the Chalice. The deacon also prepares the altar for the reception of the gifts and is responsible to assist the priest during Mass especially with instructions to the congregation.