The Council of Trent was an eighteen-year-long series of meetings by the Catholic Church to reform and codify Church doctrine. It took place in the mid-1500s, in the country now known as Italy.
There were a number of significant doctrines approved during the Council. One of the most important was the affirmation that Church rulings on interpretations of the Bible were considered final and any dissenting opinions were heresy. This decision justified the persecution of Protestantism, indirectly leading two centuries later to the founding of the United States.
Another significant decision involved the Communion Rite during Mass, in which bread and wine is said to be transformed into the flesh and blood of Jesus. Protestants and other sects claimed the act to be symbolic, while the Church claimed it to be entirely real. The Council decisively declared Communion to cause the transformation effect, and declared dissenting opinions heresy.
Another ruling involved the use of religious imagery in art, music, and literature: the Church stamped down hard on artists who used religious symbolism in any but a positive light. This caused trouble for many Classical and Renaissance artists, who created art for its own sake instead of for the Church's benefit.