Gaj's Latin alphabet (Serbo-Croatian: Gajeva latinica / Гајева латиница, pronounced [ɡâːjeva latǐnit͡sa]), also known as abeceda (Serbo-Croatian Cyrillic: абецеда, pronounced [abet͡sěːda]) or gajica (Serbo-Croatian Cyrillic: гајица, pronounced [ɡǎjit͡sa]), is the form of the Latin script used for writing all four standard varieties of Serbo-Croatian: Bosnian, Croatian, Montenegrin, and Serbian. It contains 27 individual letters and 3 digraphs. Each letter (including digraphs) represents one Serbo-Croatian phoneme, yielding a highly phonemic orthography. It closely corresponds to the Serbian Cyrillic alphabet.
The alphabet was initially devised by Croatian linguist Ljudevit Gaj in 1835 during the Illyrian movement in ethnically Croatian parts of the Austrian Empire. It was largely based on Jan Hus's Czech alphabet and was meant to serve as a unified orthography for three Croat-populated kingdoms within the Austrian Empire at the time, namely Croatia, Dalmatia and Slavonia, and their three dialect groups, Kajkavian, Chakavian and Shtokavian, which historically utilized different spelling rules. The alphabet's final form was defined in the late 19th century.
