Pashto is a member of the southeastern Iranian branch of Indo-Iranian languages spoken in Afghanistan, Pakistan and Iran. There are three main varieties of Pashto: Northern Pashto, spoken mainly in Pakistan; Southern Pashto, spoken mainly in Afghanistan; and Central Pashto, spoken mainly in Pakistan.
The exact number of Pashto speakers is not known for sure, but most estimates range from 45 million to 55 million. Pashto is the first language of between 40% and 55% (11 to 15.4 million) of the people of Afghanistan, and 10% to 28% (2.8 to 7.8 million) speak it as a second language, and the total is around 18 or 19 million.
Pashto has about 25 million speakers in Pakistan (15% of the population) in the Federally Administered Tribal Areas (FATA), and the provinces of Balochistan, Mianwali, Attock, Sindh, Punjab and Khyber Pakhtunkhwa.
There are also communities of Pashto speakers in the northeast of Iran, Tajikistan and India, as well as in the UAE, Saudi Arabia and a number of other countries.
Pashto was made the national language of Afghanistan by royal decree in 1936. Since then, the Pashto spelling system has been revised to some extent. Today both Dari and Pashto are official languages there.
Pashto first appeared in writing during the 16th century in the form of an account of Shekh Mali's conquest of Swat. It is written with a version of the Arabic script. There are two standard written forms: one based on the dialect of Kandahar, the other on the dialect of Peshawar.
The name Pashto is thought to derive from the reconstructed proto-Iranian form, parsawā 'Persian language. In northen Afghanistan speakers of Pashto are called Pakhtūn; in sourthen Afghanistan they are known as Pashtūn, and as Pathān or Afghan in Pakistan.