Glagolitic alphabet — the direct legacy of Cyril and Methodius’ mission
The Glagolitic alphabet was the first Slavic alphabet and language. The name Glagolitic comes from the Old Church Slavonic word “glagol” meaning “word”. The Glagolitic alphabet was created around the year 862 by Saint Cyril. Its preparation was initiated in response to the need to create an alphabet to record the liturgical texts in the Slavic language. The Glagolitic alphabet presents a graphic system, and during its creation Cyril drew inspiration from various alphabetical systems. There are several theories regarding the origins of the individual symbols. Part of the script is derived from the minuscule symbols of the Greek alphabet. It is an interesting fact that each letter was assigned a number, so this also represented the first Slav numerical system. The Glagolitic script gradually spread to other Slavic lands (Bohemia, Bulgaria, Croatia and others). It was later replaced by Cyrillic. A specific type of Glagolitic script (known as Croatian Glagolitic) was created in Croatia. The Glagolitic script was in regular use in Croatia until the 15th century and it persisted until the early 20th century.
(Source: Peter Ivanič, University of Constantine the Philosopher in Nitra)