The Cyrillic script or azbuka is an alphabetic writing system. It is based on the Early Cyrillic, which was developed in the First Bulgarian Empire during the 9th century AD at the Preslav Literary School. It is the basis of alphabets used in various languages, past and present, in parts of the Balkans and Northern Eurasia, especially those of Slavic origin, and non-Slavic languages influenced by Russian. As of 2011 around 252 million people in Eurasia use it as the official alphabet for their national languages. About half of them are in Russia. Cyrillic is one of the most used writing systems in the world.