Johann Tetzel

Dominican Order: An order within the Roman Catholic Church founded by Saint Dominic in France, noted for its scholarly learning and theological orthodoxy.

Indulgences: In theology, an indulgence is seen as a way to reduce the amount of punishment one has to undergo for sins which have been forgiven but still need to be atoned for.

Reformation Controversy: The period when Martin Luther's Ninety-Five Theses sparked off widespread debate about abuses in church practices and led eventually to Protestant Reformation.