There were two brother missionaries in Saloniki in the 9th century, Cyril and Methodius, who once decided to create a special alphabet for the Slavs to read Christian books. The legend says that they formed Cyrillic and Glagolitic alphabets simultaneously; but in fact, according to historical documents, it seems that was Cyril who invented Glagolitic, and his brother and his pupils already made up Cyrillic.
The Glagolitic script was absolutely the same in symbol composition and in phonetics, but completely different in shape. The script is really very unique, that is why there is no sure about where it originated from. Some linguists state that its letters are connected with Greek, and some - even with the Samaritan and the Old Hebrew writing. Alternatively, Bernard Comrie (of University of Southern California) came up with another reason for the competition between Glagolitic and Cyrillic. He theorized that Glagolitic came from cursive Greek scripts, while Cyrillic derived from Byzantine Greek uncial scripts already used in manuscripts. The students of Cyril might have found Glagolitic "undignified and unsuitable for ecclesiastical use" (Hersey) because of its cursive shapes, and derived Cyrillic from an already liturgical script.
The script was in wide use in Moravia and Bohemia since the 9th language; then it penetrated to Bulgaria, Serbia and Croatia. It was seldom used also in Kiev Russia. In most places Glagolitic gave way to Cyrillic after the 12th century. In Croatia, though, it continued to be in use until the 19th century in church. The Croatian Glagolitic is quite similar in to Old Church Slavonic Glagolitic, but it has less letters and the shape of its characters are much more rectangular.
Languages which used the script:
Slavic (Old Church Slavic, Serbo-Croatian,
Old Czech, Bulgarian).