The Cyrillic alphabet (//) is a native Slavic alphabet. It is now used to write Russian, Ukrainian, Belarusian, Rusyn, Bulgarian, Macedonian and for most South Slavic languages. It was developed in the First Bulgarian Empire in the 10th century. The Soviet Union made many non-Slavic languages in the Caucasus, Siberia, Central Asia and in borthern Russia be written in Cyrillic.
Old Church Slavonic was the original language of the Slavic people, and it was used for Russian Orthodox Church. In the 9th century, two monks, St. Cyril and St. Methodius, were missionaries in Eastern Europe. When they preached to the Slavic peoples, they invented the Glagolitic alphabet, an early form of Cyrillic.
During the 18th century, Nikolay Karamzin added Э, Й and Ё.
In 1708, Peter the Great added lowercase forms to the letters.
In 1991, Azerbaijan, Turkmenistan and Uzbekistan decided to drop the Cyrillic script and to adopt the Latin script.