"Catholic" means "Universal" in Greek, established in the Nicene Creed. Headquarters in the Vatican, led by the Pope. The Church is guided by the Holy Spirit, who also guides the Pope. The Pope cannot be wrong when he speaks officially on the subject of the Catholic faith and morals, and this infallibility has been used quite rarely. Notable example of this was in the Tome of St. Leo where it spoke about Immaculate Conception. The first Pope was Saint Peter, disciple of Jesus Christ.
Popes use a "regnal" name instead of birth names since the 6th century, when a man called "Mercury"(as in the pagan god) was elected Pope, so he named himself John II. It became customary in the 10th century, and since the death of Marcellus II in 1555, every Pope has taken a Papal name.
The main ceremony is the Mass. Catholics are normally required to go to a mass on Sundays and on Holy Days of Obligation. Examples of Holy Days are Mary(1 Jan), Assumption of Mary(15 Aug), Ascension of Jesus(40 days after Easter), All Saints Day(1 Nov), Immaculate Conception(8 Dec), and Christmas(25 Dec). Catholics tend to venerate Virgin Mary more than other Christians, almost to a queen level, for being the one chosen to bear someone who is fully man and fully God at the same time. An important Catholic prayer is the Rosary.
Catholics celebrate the seven sacraments: Baptism, Confirmation, Eucharist, Reconcilliation, Anointing of the Sitck, Holy Orders, and Holy Matrimony(Marriage). Sacraments are "outward signs started by Christ to give grace". Aka supernatural gifts that someone did nothing to deserve. Eucharist is the most important of these sacraments, since Catholics believe that Jesus becomes truly present in the form of bread and wine. Catholics interpret the Bible according to tradition, but they also state that "truth cannot contradict truth", when they translate or interpret the Bible. Catholics believe in the necessity of love, hope, and faith in order to gain salvation, but that these all come from grace. (Notably, this is where Luther disagreed)
Catholics believe in the Nicene Creed(established 325AD and 382AD).
Martin Luther originally wanted to improve Catholic theology and practices, by ending pope's indulgences and abuses of power. Then Lutheranism became a separate church by Luther and his followers following excommunication by the Pope. Luther's ideas started the Protestant Reformation. John Calvin and Ulrich Zwingli thought Luther was keeping too much Catholic doctrine and they went even further. Lutherians differ by believing the Bible is the first and only authorative source for Christian faith and teaching, and that humans are saved by Grace alone, through faith alone, because of Jesus Christ alone. These main points would be summed up in 1530 by Philip Melanchthon in "The Augsburg Confession". Unlike Catholics, Lutheran pastors and bishops are allowed to marry, do not pray for intercession with the saints(and Mary), and reject the authority and infallibility of the Pope and Catholic Magisterium. It's similar to Catholicism in that it includes the liturgy and the doctrines of the real presence of the Eucharist, baptism and original sin.
Named after John Calvin, a French exile in Geneva, Switzerland. The OG Calvinists were Martin Bucer, Heinrich Bullinger, Peter Martyr Vermigli, and Huldrych Zwingli. From England, Thomas Cranmer and John Jewel. Calvinism today is most famous for their doctrines of predestination and total depravity. Calvinism began when he published "Institutes of the Christian Religion" in 1536. Calvin signed the Lutheran Augsburg Confession in 1540, but he was mostly involved in the Swiss Reformation, which followed Zwingli and then Calvin instead. True Calvinism doesn't teach that God chooses people who will be saved, but that God recreates men with a new nature, that love God and hate sin. Also teaches that if God does not choose to save someone, he can do nothing to be saved. Calvinism spread from Geneva into Scotland, Netherlands, parts of Germany, and by the settlers of New England in America, and the Dutch colonisers of South Africa(the Boers/Afrikaners).