Calvinism belongs to the Reformed tradition of Protestantism. This tradition goes back to John Calvin and other theologians.

Important Calvinists from Europe include: Martin Bucer, Heinrich Bullinger, Peter Martyr Vermigli, and Huldrych Zwingli, and from England, reformers Thomas Cranmer and John Jewel. Because John Calvin had great influence and played an important role in the confessional and ecclesiastical debates throughout the 17th century, the tradition generally became known as Calvinism.

Today, this term also means the doctrines and practices of the Reformed churches, of which Calvin was an early leader, and the system is perhaps best known for its doctrines of predestination and total depravity.

Historical background
John Calvin's international influence on the development of the doctrines of the Protestant Reformation began at the age of 25, when he started work on his first edition of the Institutes of the Christian Religion in 1534 (published 1536). Alongside the work he contributed to confessional documents for use in churches, Calvin's beliefs and practices left a direct influence on Protestantism. He is only one of many people to influence the doctrines of the Reformed churches, but he eventually became one of the most prominent theologians.

The rising importance of the Reformed churches, and of Calvin, happened in the second phase of the Protestant Reformation, when evangelical churches began to form, after Martin Luther, another important Reformer, was excommunicated from the Roman Catholic Church. Calvin was a French exile in Geneva. He had signed the Lutheran Augsburg Confession in 1540, but his importance came from the Swiss Reformation. This was not Lutheran, but followed Huldrych Zwingli and then Calvin.

True Calvinism (historical Calvinism) does not teach that God chooses who will be saved and who will not be saved. Instead, it teaches that for God's own glory, He recreates men with a new nature - a nature that loves God and hates sin - instead of men keeping their old nature, as if they kept their old nature, they would not want to follow God. Historical Calvinism also teaches that if God did not choose to save someone, there would be no-one to be saved.

The spread of Calvinism
Although much of Calvin's practice was in Geneva, his publications spread his ideas of a reformed church to many parts of Europe. Calvinism became the theology of most Christians in Scotland (see John Knox), the Netherlands, and parts of Germany, and was influential in France, Hungary, Transylvania, and Poland. Calvinism was popular as well for some time in Scandinavia, especially Sweden, but was rejected in favor of Lutheranism after the synod of Uppsala in 1593.

Most settlers in the American Mid-Atlantic and New England were Calvinists, including the Puritans and Dutch settlers of New Amsterdam (New York). Dutch Calvinist settlers were also the first successful European colonizers of South Africa, beginning in the 17th century, who became known as Boers or Afrikaners.

Some of the largest Calvinist communions were started by 19th and 20th century missionaries; especially large are those in Korea and Nigeria.

Resources 

John Wesley (2001). Calvinism Calmly Considered. 
C. Gordon Olson (2002). Beyond Calvinism and Arminianism: An Inductive, Mediate Theology of Salvation. Global Gospel Publishers.

Other websites 
 "Calvinist Childrearing Methodology" from A Study of the First Maternal Association of Utica, New York, 1824-1833 by Elizabeth Shanklin
"The Impact of Calvinism on Sixteenth Century Culture" 1967 By Dr. W. Stanford Reid

Calvinist websites
Center for Reformed Theology and Apologetics - offers many materials from a Calvinist perspective.
Monergism - classic articles and resources; claims to have the largest collection of Reformed/Calvinist resources on the Internet.
Calvinism Index  by Colin Maxwell

Calvinism and other theological systems
What is Calvinism? - A Summary of the Presbyterian Religion.
Calvinism & Arminianism - a brief comparison of Calvinism and Arminianism from The Five Points of Calvinism - Defined, Defended, Documented by Steele

 
John Calvin
Christian movements and denominational families
Protestant Reformation