Persian, also known as Farsi, is a Western Iranian language belonging to the Iranian branch of the Indo-Iranian subdivision of the Indo-European languages. Persian is a pluricentric language predominantly spoken and used officially within Iran, Afghanistan, and Tajikistan in three mutually intelligible standard varieties, namely Iranian Persian (officially known as Farsi), Afghan Persian (officially known as Dari since 1964), and Tajiki Persian (officially known as Tajik since 1999).Siddikzoda, S. "Tajik Language: Farsi or not Farsi?" in Media Insight Central Asia #27, August 2002. It is also spoken natively in the Tajik variety by a significant population in Uzbekistan, as well as within other regions with a Persianate history in the cultural sphere of Greater Iran. It is written officially within Iran and Afghanistan in the Persian alphabet, a derivative of the Arabic script, and within Tajikistan in the Tajik alphabet, a derivative of the Cyrillic script.

Modern Persian is a continuation of Middle Persian, an official language of the Sasanian Empire (224–651 CE), itself a continuation of Old Persian, which was used in the Achaemenid Empire (550–330 BCE). It originated in the region of Fars (Persia) in southwestern Iran.

Throughout history, Persian was considered prestigious by various empires centered in West Asia, Central Asia, and South Asia. Old Persian is attested in Old Persian cuneiform on inscriptions from between the 6th and 4th century BCE. Middle Persian is attested in Aramaic-derived scripts (Pahlavi and Manichaean) on inscriptions and in Zoroastrian and Manichaean scriptures from between the third to the tenth centuries (see Middle Persian literature). New Persian literature was first recorded in the ninth century, after the Muslim conquest of Persia, since then adopting the Perso-Arabic script.

Persian was the first language to break through the monopoly of Arabic on writing in the Muslim world, with Persian poetry becoming a tradition in many eastern courts. It was used officially as a language of bureaucracy even by non-native speakers, such as the Ottomans in Anatolia, the Delhi Sultanates and Mughals in the Indian subcontinent, and the Pashtuns in Afghanistan. It influenced languages spoken in neighboring regions and beyond, including other Iranian languages, the Turkic, Armenian, Georgian, Greek and Indo-Aryan languages. It also exerted some influence on Arabic, while borrowing a lot of vocabulary from it in the Middle Ages.: "The language known as New Persian, which usually is called at this period (early Islamic times) by the name of Dari or Farsi-Dari, can be classified linguistically as a continuation of Middle Persian, the official religious and literary language of Sassanian Iran, itself a continuation of Old Persian, the language of the Achaemenids. Unlike the other languages and dialects, ancient and modern, of the Iranian group such as Avestan, Parthian, Soghdian, Kurdish, Balochi, Pashto, etc., Old Persian, Middle Persian, and New Persian represent one and the same language at three states of its history. It had its origin in Fars (the true Persian country from the historical point of view) and is differentiated by dialectical features, still easily recognizable from the dialect prevailing in north-western and eastern Iran."

Some of the world's most famous pieces of literature from the Middle Ages, such as the Shahnameh by Ferdowsi, the works of Rumi, the Rubaiyat of Omar Khayyam, the of Nizami Ganjavi, The Divân of Hafez, The Conference of the Birds by Attar of Nishapur, and the miscellanea of Gulistan and Bustan by Saadi Shirazi, are written in Persian. Some of the prominent modern Persian poets were Nima Yooshij, Ahmad Shamlou, Simin Behbahani, Sohrab Sepehri, Rahi Mo'ayyeri, Mehdi Akhavan-Sales, and Forugh Farrokhzad.

There are approximately 130 million Persian speakers worldwide, including Persians, Lurs, Tajiks, Hazaras, Iranian Azeris, Iranian Kurds, Balochs, Tats, Afghan Pashtuns, and Aimaqs. The term Persophone might also be used to refer to a speaker of Persian.

Classification Persian is a member of the Western Iranian group of the Iranian languages, which make up a branch of the Indo-European languages in their Indo-Iranian subdivision. The Western Iranian languages themselves are divided into two subgroups: Southwestern Iranian languages, of which Persian is the most widely spoken, and Northwestern Iranian languages, of which Kurdish and Balochi are the most widely spoken.

Name The term Persian is an English derivation of Latin , the adjectival form of , itself deriving from Greek (),. a Hellenized form of Old Persian (), which means "Persia" (a region in southwestern Iran, corresponding to modern-day Fars). According to the Oxford English Dictionary, the term Persian as a language name is first attested in English in the mid-16th century.Oxford English Dictionary online, s.v. "Persian", draft revision June 2007.

, which is the Persian word for the Persian language, has also been used widely in English in recent decades, more often to refer to Iran's standard Persian. However, the name Persian is still more widely used. The Academy of Persian Language and Literature has maintained that the endonym is to be avoided in foreign languages, and that Persian is the appropriate designation of the language in English, as it has the longer tradition in western languages and better expresses the role of the language as a mark of cultural and national continuity. Iranian historian and linguist Ehsan Yarshater, founder of the Encyclopædia Iranica and Columbia University's Center for Iranian Studies, mentions the same concern in an academic journal on Iranology, rejecting the use of in foreign languages.

Etymologically, the term derives from its earlier form ( in Middle Persian), which in turn comes from the same root as the English term Persian. In the same process, the Middle Persian toponym ("Persia") evolved into the modern name Fars. The phonemic shift from to is due to the influence of Arabic in the Middle Ages, from the lack of the phoneme in Standard Arabic.Perry, John R. "Persian morphology." Morphologies of Asia and Africa 2 (2007): 975–1019.Seraji, Mojgan, Beáta Megyesi, and Joakim Nivre. "A basic language resource kit for Persian." Eight International Conference on Language Resources and Evaluation (LREC 2012), 23–25 May 2012, Istanbul, Turkey. European Language Resources Association, 2012.Sahranavard, Neda, and Jerry Won Lee. "The Persianization of English in multilingual Tehran." World Englishes (2020).

Standard varieties' names The standard Persian of Iran has been called, apart from Persian and Farsi, by names such as Iranian Persian and Western Persian, exclusively. The official language of Iran is designated simply as Persian (, ).

The standard Persian of Afghanistan has been officially named Dari (, ) since 1958. Also referred to as Afghan Persian in English, it is one of Afghanistan's two official languages, together with Pashto. The term Dari, meaning "of the court", originally referred to the variety of Persian used in the court of the Sasanian Empire in capital Ctesiphon, which spread to the northeast of the empire and gradually replaced the former Iranian dialects of Parthia (Parthian).

Tajik Persian (, ), the standard Persian of Tajikistan, has been officially designated as Tajik (, ) since the time of the Soviet Union. It is the name given to the varieties of Persian spoken in Central Asia in general.

ISO codes The international language-encoding standard ISO 639-1 uses the code fa for the Persian language, as its coding system is mostly based on the native-language designations. The more detailed standard ISO 639-3 uses the code fas for the dialects spoken across Iran and Afghanistan. This consists of the individual languages Dari (prs) and Iranian Persian (pes). It uses tgk for Tajik, separately.

History In general, the Iranian languages are known from three periods: namely Old, Middle, and New (Modern). These correspond to three historical eras of Iranian history; Old era being sometime around the Achaemenid Empire (i.e., 400–300 BCE), Middle era being the next period most officially around the Sasanian Empire, and New era being the period afterward down to present day. vi(2). Documentation.

According to available documents, the Persian language is "the only Iranian language" for which close philological relationships between all of its three stages are established and so that Old, Middle, and New Persian represent one and the same language of Persian; that is, New Persian is a direct descendant of Middle and Old Persian.cf. vi(2). Documentation. Excerpt 1: "Only the official languages Old, Middle, and New Persian represent three stages of one and the same language, whereas close genetic relationships are difficult to establish between other Middle and Modern Iranian languages. Modern Yaḡnōbi belongs to the same dialect group as Sogdian, but is not a direct descendant; Bactrian may be closely related to modern Yidḡa and Munji (Munjāni); and Wakhi (Wāḵi) belongs with Khotanese. Excerpt 2: New Persian, the descendant of Middle Persian and official language of Iranian states for centuries." Gernot Windfuhr considers new Persian as an evolution of the Old Persian language and the Middle Persian language, p. 82. "The evolution of Persian as the culturally dominant language of major parts of the Near East, from Anatolia and Iran, to Central Asia, to northwest India until recent centuries, began with the political domination of these areas by dynasties originating in southwestern province of Iran, Pars, later Arabicised to Fars: first the Achaemenids (599–331 BC) whose official language was Old Persian; then the Sassanids (c. AD 225–651) whose official language was Middle Persian. Hence, the entire country used to be called Perse by the ancient Greeks, a practice continued to this day. The more general designation 'Iran(-shahr)" derives from Old Iranian aryanam (Khshathra)' (the realm) of Aryans'. The dominance of these two dynasties resulted in Old and Middle-Persian colonies throughout the empire, most importantly for the course of the development of Persian, in the north-east i.e., what is now Khorasan, northern Afghanistan, and Central Asia, as documented by the Middle Persian texts of the Manichean found in the oasis city of Turfan in Chinese Turkistan (Sinkiang). This led to certain degree of regionalisation". but also states that none of the known Middle Persian dialects is the direct predecessor of Modern Persian.Comrie, Bernard (1990) The major languages of South Asia, the Middle East and Africa, Taylor & Francis, p. 82Barbara M. Horvath, Paul Vaughan, Community languages, 1991, p. 276 Ludwig Paul states: "The language of the Shahnameh should be seen as one instance of continuous historical development from Middle to New Persian."L. Paul (2005), "The Language of the Shahnameh in historical and dialectical perspective", p. 150: "The language of the Shahnameh should be seen as one instance of continuous historical development from Middle to New Persian.", in

The known history of the Persian language can be divided into the following three distinct periods:

Old Persian

As a written language, Old Persian is attested in royal Achaemenid inscriptions. The oldest known text written in Old Persian is from the Behistun Inscription, dating to the time of King Darius I (reigned 522–486 BCE). Examples of Old Persian have been found in what is now Iran, Romania (Gherla), Armenia, Bahrain, Iraq, Turkey, and Egypt.Kent, R. G.: "Old Persian: Grammar Texts Lexicon", page 6. American Oriental Society, 1950. Old Persian is one of the earliest attested Indo-European languages.