A Missionary is a term commonly used to describe a person who is spreading the word of God and seeking to convert people to his religion.
The Missionary may be a minister or preist but is often a lay person. A missionary may also describe a lay person who is doing work on behalf of his Church. This work may be disaster relief, establishing clean water sources, assisting in cottage industries and marketing, education or health programs. Some religions mandate or encourage a mission by each member when they turn 18 or shortly thereafter.
Missions may be to foreign countries or in a local area depending on the age level and interest of the missionary.