The essential function of presenting knowledge of the Word of God, the message of Jesus Christ, is attained through orally instructing, explaining, and admonishing the people by means of preaching.
Preaching is the oral communication or instruction on the meaning of the Scriptures and other aspects of the Faith.
The office of preaching has always been considered a preeminent ministry in the Church. According to present legislation of the Church, the Pope and bishops are allowed to preach anywhere.
Priests and deacons possess the faculty to also preach, but not the inherent right to preach anywhere without the presumed permission of the pastor or rector of another place.
The homily is the most important form of preaching. It is the address given after the Gospel during the celebration of Mass.
Current custom is to limit the homily to ten to fifteen minutes. However, the solemnity of the occasion may require one of greater length.
A homily is recommended at all Masses and is required at Masses celebrated on Sundays and holy days of obligation. It is forbidden for anyone but a bishop, priest or deacon to give the homily. (8:16)