Old Church Slavonic is an ancient Slavic language that was used in the early Christian church. It was developed in the 9th century by the brothers Cyril and Methodius, who created it to translate the Bible and other religious texts for the Slavic peoples. This language played a crucial role in spreading Christianity and literacy among the Slavs. As the first Slavic literary language, Old Church Slavonic influenced many modern Slavic languages, including Russian, Bulgarian, and Serbian. Although it is no longer spoken as a native language, it is still used in some religious contexts, preserving its historical and cultural significance.