While all Christians are called to serve others, the deacon is an official sign of this service and he solemnly promises to be a living example of such service for others. Through Holy Orders, the deacon acquires a special relationship to the bishop. His ministry of charity, word, and sacrament enables the Church to be a credible sign of the Servant Christ in the world. Men who are to be ordained priests are ordained deacons prior to priesthood. Both transitional and permanent deacons share in the Order of Deacon.
Married men can become deacons.
Single men who are ordained deacons take a promise of celibacy, similar to the priest's promise of celibacy, and may not marry once they are ordained. If married, the deacon candidate should be in a stable marriage for a number or years and have the expressed consent and support of his wife. His children should also be of such an age and adjustment as not to be unduly affected by their father's pursuit of a life that involves special apostolic commitments. This is a complex question and certainly deserves more than a short answer. Each shares uniquely in the ministry of Christ to His people, the Church.