The Cyrillic script ( sih-RIL-ik), otherwise known as the Slavonic script or simply the Slavic script, is a writing system used for various languages across Eurasia. It is the designated national script in various Slavic, Turkic, Mongolic, Uralic, Caucasian and Iranic-speaking countries in Southeastern Europe, Eastern Europe, the Caucasus, Central Asia, North Asia, and East Asia.

As of 2019, around 250 million people in Eurasia use Cyrillic as the official script for their national languages, with Russia accounting for about half of them. With the accession of Bulgaria to the European Union on 1 January 2007, Cyrillic became the third official script of the European Union, following the Latin and Greek alphabets.

The Early Cyrillic alphabet was developed during the 9th century AD at the Preslav Literary School in the First Bulgarian Empire during the reign of tsar Simeon I the Great, probably by disciples of the two Byzantine brothers Saint Cyril and Saint Methodius, who had previously created the Glagolitic script. The script is named in honor of Saint Cyril.