Cyril and Methodius were two Byzantine brothers born in the 9th century, known for their missionary work among the Slavic peoples. They created the Glagolitic alphabet, the first alphabet used to transcribe the Old Church Slavonic language, which helped spread Christianity and literacy in the region. Their efforts laid the foundation for the development of Slavic cultures and languages. Cyril and Methodius are often referred to as the "Apostles to the Slavs" and are celebrated in various countries, particularly in Slovakia and Bulgaria, for their contributions to education and religious life.