Lay ministers are generally chosen in small communities where it is difficult to find professional clergy to serve roles, and in which lay ministers are appropriate to fulfill the pastoral duties (e.g: a Catholic hospital chaplain does not have to be an ordained priest).
In most Protestant churches, deacons, Sunday School teachers, youth ministers, and praise teams are considered lay ministry positions.
The lay ministry's role and importance varies, depending on confession and regional situation: The United States Conference of Catholic Bishops uses the term "lay ecclesial ministry" for a category of non-ordained (non-priest) pastoral ministers.
[1] The idea of volunteer, unpaid leadership and service is very important in the Church of Jesus Christ of Latter-day Saints.
Ordinary church members may receive "callings" to serve in any number of positions, from leadership and administration to teaching sunday school classes for adults or for children.