Serbian is the standard variety of the Serbo-Croatian language mainly used by Serbs. It is the official and national language of Serbia, one of the three official languages of Bosnia and Herzegovina, and co-official in Montenegro and Kosovo. It is a recognized minority language in Croatia, North Macedonia, Romania, Hungary, Slovakia, and the Czech Republic.

Serbian is based on the most widespread dialect of Serbo-Croatian, Shtokavian (more specifically on the dialects of Šumadija-Vojvodina and Eastern Herzegovina), which is also the basis of standard Croatian, Bosnian, and Montenegrin varieties. Reflecting this shared basis, the Declaration on the Common Language of Croats, Bosniaks, Serbs, and Montenegrins was issued in 2017. The other dialect spoken by Serbs is Torlakian in southeastern Serbia, which is transitional to Macedonian and Bulgarian.

Serbian is the only European standard language whose speakers are fully functionally digraphic (i.e., its speakers can read and write in Cyrillic and Latin alphabets interchangeably). The Serbian Cyrillic alphabet was standardized in 1814 by Serbian linguist Vuk Karadžić, who reformed it based on phonemic principles. The Latin alphabet used for Serbian was designed by the Croatian linguist Ljudevit Gaj in the 1830s based on the Czech system with a one-to-one grapheme-phoneme correlation between the Cyrillic and Latin orthographies, resulting in a parallel orthographic system.

Serbian is a standard variety of Serbo-Croatian, a Slavic language (Indo-European), of the South Slavic subgroup. Other standard varieties of Serbo-Croatian are Bosnian, Croatian, and Montenegrin. "An examination of all the major 'levels' of language shows that BCS is clearly a single language with a single grammatical system." It has lower intelligibility with the Eastern South Slavic languages Bulgarian and Macedonian, than with Slovene (Slovene is part of the Western South Slavic subgroup, but there are still significant differences in vocabulary, grammar and pronunciation to the standard varieties of Serbo-Croatian, although it is closer to the Kajkavian and Chakavian dialects of Serbo-Croatian).

Speakers by country:

Serbian was the official language of Montenegro until October 2007, when the new Constitution of Montenegro replaced the Constitution of 1992. Amid opposition from pro-Serbian parties, Montenegrin was made the sole official language of the country, and Serbian was given the status of a language in official use along with Bosnian, Albanian, and Croatian.

In the 2023 Montenegrin census, 43.18% declared Serbian to be their native language, while Montenegrin was declared by 34.52% of the population.

Standard Serbian language uses both Cyrillic (ћирилица, ćirilica) and Latin script (latinica, латиница). Serbian is a rare example of synchronic digraphia, a situation where all literate members of a society have two interchangeable writing systems available to them. Media and publishers typically select one alphabet or the other. In general, the alphabets are used interchangeably; except in the legal sphere, where Cyrillic is required, there is no context where one alphabet or another predominates.