Persian (local names: فارسی, Fārsi IPA: [fɒːɾˈsi]; or پارسی, Pārsi IPA: [pɒːɾˈsi]) is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is widely spoken in Iran, Afghanistan, Tajikistan, Uzbekistan and to some extent in Armenia, Iraq, Pakistan, India, Bahrain, and Oman. Persian, which usually is called by the natives as فارسی Fārsi, Pārsi, Dari or Pārsi-ye-Dari (Dari Persian), can be classified linguistically as a continuation of Middle Persian, the official religious and literary language of Sassanid Iran, itself a continuation of Old Persian, the language of the Persian Empire in the Achaemenids era. Persian is a pluricentric language and its grammar is similar to that of many contemporary European languages. The Persian language has been a medium for literary and scientific contributions to the eastern half of the Muslim world.

Persian has had a considerable influence on neighboring languages, particularly the Turkic languages in Central Asia, Caucasus, and Anatolia, neighboring Iranian languages, as well as Armenian, Arabic and other languages. It has also exerted a strong influence on South Asian languages, especially Urdu, as well as Hindi, Punjabi, Sindhi, Saraiki, Sylheti, and Bengali.

Persian, the more widely used name of the language in English, is an Anglicized form derived from Latin *Persianus < Latin Persia < Greek Πέρσις Pérsis, a Hellenized form of Old Persian Parsa. According to the Oxford English Dictionary, the term Persian seems to have been first used in English in the mid-16th century. Native Persian speakers call it "Pârsi" (local name) or Fârsi. Fârsi is the arabicized form of Pârsi, due to a lack of the 'p' phoneme in Standard Arabic. In English, this language is historically known as "Persian", though some Persian-speakers migrating to the West continued to use "Farsi" to identify their language in English and the word gained some currency in English-speaking countries. "Farsi" is encountered in some linguistic literature as a name for the language, used both by Iranian and by foreign authors. According to the OED, the term Farsi was first used in English in the mid-20th century. The Academy of Persian Language and Literature has declared that the name "Persian" is more appropriate, as it has the longer tradition in the western languages and better expresses the role of the language as a mark of cultural and national continuity. Some Persian language scholars have also rejected the usage of "Farsi" in their articles.