The word “mission” has a variety of meanings as used by the Church, all of which stem from the apostolic commission given to the Apostles by Christ, and are concerned with the teaching role of the Church in its mission to all people.
The parish mission, a so-called popular mission at the parish level, is a series of instructions, sermons, and devotions conducted in a parish for the spiritual welfare of the people. They usually last for several days and may be conducted annually.
For a parish mission, the parish leadership will typically invite a guest speaker from outside the parish to lead or facilitate sessions to inspire, renew, transform and awaken one’s faith in Jesus Christ. (8:46)