Jan Hus in the context of "Hussite Wars"

The Czechoslovak Hussite Church (Czech: Církev československá husitská, CČSH or CČH; Slovak: Cirkev československá husitská) is a Christian church that separated from the Catholic Church after World War I in Czechoslovakia.

Both the Czechoslovak Hussite Church and Moravian Church trace their tradition back to the Hussite reformers and acknowledge Jan Hus (John Huss) as their predecessor. It was well-supported by Czechoslovakia's first president, Tomáš Garrigue Masaryk, who himself belonged to the Evangelical Church of Czech Brethren.

Gaj's Latin alphabet (Serbo-Croatian: Gajeva latinica / Гајева латиница, pronounced [ɡâːjeva latǐnit͡sa]), also known as abeceda (Serbo-Croatian Cyrillic: абецеда, pronounced [abet͡sěːda]) or gajica (Serbo-Croatian Cyrillic: гајица, pronounced [ɡǎjit͡sa]), is the form of the Latin script used for writing all four standard varieties of Serbo-Croatian: Bosnian, Croatian, Montenegrin, and Serbian. It contains 27 individual letters and 3 digraphs. Each letter (including digraphs) represents one Serbo-Croatian phoneme, yielding a highly phonemic orthography. It closely corresponds to the Serbian Cyrillic alphabet.

The alphabet was initially devised by Croatian linguist Ljudevit Gaj in 1835 during the Illyrian movement in ethnically Croatian parts of the Austrian Empire. It was largely based on Jan Hus's Czech alphabet and was meant to serve as a unified orthography for three Croat-populated kingdoms within the Austrian Empire at the time, namely Croatia, Dalmatia and Slavonia, and their three dialect groups, Kajkavian, Chakavian and Shtokavian, which historically utilized different spelling rules. The alphabet's final form was defined in the late 19th century.

The Council of Constance (Latin: Concilium Constantiense; German: Konzil von Konstanz) was an ecumenical council of the Catholic Church that was held from 1414 to 1418 in the Bishopric of Constance (Konstanz) in present-day Germany. This was the first ecumenical council convened in the Holy Roman Empire. The council ended the Western Schism by deposing or accepting the resignation of the remaining papal claimants and by electing Pope Martin V. It was the last papal election to take place outside of Italy.

The council also condemned Jan Hus as a heretic and facilitated his execution; and it ruled on issues of national sovereignty and the rights of pagans and just war in response to a conflict between the Grand Duchy of Lithuania, the Kingdom of Poland and the Order of the Teutonic Knights.

The Bohemian Reformation (also known as the Czech Reformation or Hussite Reformation), preceding the Reformation of the 16th century, was a Christian movement in the late medieval and early modern Kingdom and Crown of Bohemia (mostly what is now present-day Czech Republic, Silesia, and Lusatia) striving for a reform of the Catholic Church. Lasting for more than 200 years, it had a significant impact on the historical development of Central Europe and is considered one of the most important religious, social, intellectual and political movements of the early modern period. The Bohemian Reformation produced the first national church separate from Roman authority in the history of Western Christianity, the first apocalyptic religious movement of the early modern period, and the first pacifist Protestant church.

The Bohemian Reformation included several theological strains that developed over time. Although it split into many groups, some characteristics were shared by all of them – communion under both kinds, distaste for the wealth and power of the church, emphasis on the Bible preached in a vernacular language and on an immediate relationship between man and God. The Bohemian Reformation included particularly the efforts to reform the church before Hus, the Hussite movement (including e.g. Taborites and Orebites), the Unity of the Brethren and Utraquists or Calixtines.

The Hussites (Czech: Husité or Kališníci, "Chalice People"; Latin: Hussitae) were a Czech proto-Protestant Christian movement influenced by both the Byzantine Rite and John Wycliffe that followed the teachings of reformer Jan Hus (fl. 1401–1415), a part of the Bohemian Reformation.

The Czech lands had originally been Christianized by Byzantine Greek missionaries Saints Cyril and Methodius, who introduced the Byzantine Rite in the Old Church Slavonic liturgical language and the Byzantine tradition of Communion in both kinds administered by the holy spoon. Over the centuries that followed, however, the Roman Rite in Ecclesiastical Latin, which is less easily understood than Slavonic by native speakers of Old Czech, was imposed upon the Czech people despite considerable public resistance, by German-speaking bishops, beginning with Wiching, from the Holy Roman Empire. (See also Sázava Monastery). As a cultural memory of both communion in both kinds and the Divine Liturgy in a language closer to the vernacular is believed to have survived well into the Renaissance, the ideas of Jan Hus and others like him swiftly gained a wide public following. After the trial and execution of Hus at the Council of Constance, a series of crusades, civil wars, victories and compromises between various factions with different theological agendas broke out. At the end of the Hussite Wars (1420–1434), the now Catholic-supported Utraquist side came out victorious from protracted conflict against Jan Žižka and the Taborites, who embraced the more radical theological teachings of John Wycliffe and the Lollards, and became the dominant Hussite group in Bohemia.

Czech orthography is a system of rules for proper formal writing (orthography) in Czech. The earliest form of separate Latin script specifically designed to suit Czech was devised by Czech theologian and church reformist Jan Hus, the namesake of the Hussite movement, in one of his seminal works, De orthographia bohemica (On Bohemian orthography).

The modern Czech orthographic system is diacritic, having evolved from an earlier system which used many digraphs (although one digraph has been kept - ch). The caron (known as háček in Czech) is added to standard Latin letters to express sounds which are foreign to Latin. The acute accent is used for long vowels.

Proto-Protestantism, also called pre-Protestantism, refers to individuals and movements that propagated various ideas later associated with Protestantism before 1517, which historians usually regard as the starting year for the Reformation era. The relationship between medieval sects and Protestantism is an issue that has been debated by historians.

Successionism is the further idea that these proto-Protestants are evidence of a continuous hidden church of true believers, despite their manifest differences in belief.