Bulgarian (ISO 639 codes bul, bg) is an Indo-European language, a member of the South branch of the Slavic languages, along with Macedonian, Serbo-Croatian, and Slovenian. The Bulgarian language is closely related to the Macedonian language. Some linguists even claim that they are the same language.
Bulgarian is the most widely spoken language in Bulgaria. Also spoken in Canada, Greece, Hungary, Israel, Moldova, Romania, Serbia, Turkey, Ukraine and USA with an estimated total of 9 million native speakers.
Bulgarian is the oldest written Slavic language. Historically it is divided into Old Bulgarian (9th to 11th century), Middle Bulgarian (12th to 15th century) and Modern Bulgarian (16th century onwards). Present-day written language was standardised in the 19th century. Some words and structure remain from the language of the Bulgars, the Central Asian people who moved into present-day Bulgaria and eventually adopted the local Slavic language. Their old Bulgar was otherwise unrelated to Bulgarian.
Bulgarian demonstrates several linguistic innovations that set it apart from all other Slavic languages, such as the elimination of noun declension, the development of a suffix definite article (possibly inherited from the Bulgar language, or taken from Albanian), the lack of verb infinitive, and the retention and further development of the Proto-Slavic verb system. There are various verb forms to express non-witnessed, retold, and doubtful action.