Modern Persian is spoken as a first language in Iran, Afghanistan, Tajikistan, and by some speakers in India. In Iran, Persian, which is called Farsi there, is the language of the urban centers. It is the first language of slightly less than half of the population and enjoys the status of official language for political and economic purposes. Persian is also an official language in Afghanistan, where it is called Dari, sharing official status there with another Iranian language, Pashto. Finally in Tajikistan, Persian, there called Tajiki and written in a modified Cyrillic alphabet, is also the official language.

There is a great deal of dialectal variation in Modern Persian. In Iran, every urban center has its specific dialect: to name a few, Esfehani (dialect of Esfahan), Kermani (dialect of Kerman), Mashhadi (dialect of Mashhad), Shirazi (dialect of Shiraz) and Tehrani (dialect of the capital, Tehran). It is the Tehrani dialect which enjoys the status of standard dialect, and is used in the educational and communication media as well as in governmental offices.

Three periods have been distinguished in the historical development of Persian:

1. Old Persian
6th - 3rd Centuries B.C.

Old Persian was the official language of the Achaemenian Empire. The language has been preserved by documents in cuneiform inscriptions of that dynasty. The limited corpus of approximately 600 words which has remained indicates that Old Persian, unlike Modern Persian, was a highly inflected language, with seven cases, three genders and a dual form in addition to the singular and plural. Although mainly an SOV (subject object verb) language, Old Persian displays some SVO patterns in subordinate clauses and some VSO pattern in main clauses.

2. Middle Persian
3rd Century B.C. to 9th Century A.D.

Middle Persian was used in the Southwestern part of Iran. It was the official language of the Sassanide Dynasty. There has been an abundance of material preserved from Middle Persian. Inflectionally, Middle Persian is much simpler than Old Persian. It has neither gender nor case and has lost the dual number. The relationship between Middle Persian and Modern Persian is quite close. The word order of Middle Persian is the same as Modern Persian as well; they both follow the SOV order.

3. Modern Persian
9th Century A.D. to present

The earliest examples of Modern Persian date from the ninth century. The language has evolved towards a simplified analytic type with respect to noun declensions and verbal conjugations. As far as the historical development of Modern Persian is concerned, the five stages listed below have been distinguised by Windfuhr (1978):