It was right in the middle of the Bosporus, Black Sea and the Mediterranean Sea. So, all trade between North Africa, Asia and Europe, had to pass through the capital (Constantinople), causing the Byzantine Empire to become very wealthy due to taxes they charged between the trading.
Religious orders were formed that aimed to build allegiance to Rome and the papacy, and to educate people in Catholic teaching. The Society of Jesus, known as the Jesuits for short, was a key order of this sort. The order was founded by Ignatius of Loyola in 1534, along with Francis Xavier and several others.
The Council of Trent served to reform some abuses that were acknowledged by the Catholic Church. For instance, the Council of Trent put a stop to the selling of indulgences. But more than anything, the meeting of Roman Catholic church leaders reasserted the full authority of Roman power and doctrine in opposition to the Protestant threat. The Council of Trent held meetings over a span of years from 1545 to 1563.
The Roman Inquisition was founded in 1542 to act as an investigative body regarding threats to Rome's teachings. About a century later, Galileo would be one of the most famous persons tried by the Roman Inquisition. The efforts of the Roman Catholic Church in the 16th century have continued to impact both Catholicism and Protestantism. Faithful Catholics see the "Catholic Reformation" (which included the items described above) as a healthy resurgence of Rome's spiritual authority. Protestants have tended to see Rome's efforts as oppressive, convincing them that breaking off relationships with Rome was the right thing to do. There have been some efforts in recent history to build ecumenical ties between Catholics and Protestants, but mostly the two sides have continued to pursue their separate missions apart from one another.
In conclusion, The Roman Catholic Church responded to the spread of Protestantism in the 16th century in several ways, intending to strengthen its own stance and its hold on church power.
