The Early Cyrillic alphabet was a writing system developed in Bulgaria during the 10th century A.D. for the writing of Old Church Slavonic. With Christianity having been made the official state religion in 864, King Boris I commissioned the creation of the alphabet. Climent of Ochrid developed the alphabet and named it for his teacher, St. Cyril, a missionary who, along with his brother, Methodius, is credited with inventing the Glagolitic alphabet, an earlier Slavic alphabet and an influence on this one. The alphabet also shows influence from the Greek and Latin alphabets. In the following centuries, the Early Cyrillic was replaced by a later form, the Modern Cyrillic alphabet, which is still widely in use throughout Asia and Eastern Europe.
Ouku: The first form developed into a vertical ligature, shown in the second form.
Ęsǔ: In Russian, this glyph is called ЮСЪ МАЛЫЙ (jusǔ malūi; IPA: [jusʌ malyi]).
Jęsǔ: In Russian, this glyph is called ЮСЪ МАЛЫЙ ЁТИРОВАНИЙ (jusǔ malūi jotirovanij; IPA: [jusʌmalyi jotirovanij]). This glyph is rare.
Ǫsǔ: In Russian, this glyph is called ЮСЪ БОЛЬШИЙ (jusǔ bolǐšij; IPA: [jusʌ bolyʃiː]). This glyph is rare.
Jǫsǔ: In Russian, this glyph is called ЮСЪ БОЛЬШИЙ ЁТИРОВАНИЙ (jusǔ bolǐšij jotirovanij; IPA: [jusʌ bolyʃiː jotirovanij]). This glyph is rare.
Đerv: This letter is present in the Glagolitic alphabet, but its sound had disappeared by the time Cyrillic started to be used. In Russian, Gherv or Dzherv is only used in modern scientific texts where Cyrillic is used to transliterate Glagolitic; the character is found in some Balkan languages, notably the languages of the former Yugoslavia.
Each letter also had a numeric value, inherited from the corresponding Greek letter. A titlo over a sequence of letters indicated their use as a number. See Cyrillic numerals, Titlo.
Several diacritics, adopted from Polytonic Greek orthography, were also used (these may not appear correctly in all web browsers; they are supposed to be directly above the letter, not off to its upper right):
