The Eastern, or Afghan, language most commonly refers to Pashto, one of the two official languages of Afghanistan, the other being Dari (a variety of Persian). Pashto is an Indo-Iranian language within the larger Indo-European family and is spoken by the Pashtun people, the largest ethnic group in Afghanistan. It is also spoken in parts of Pakistan, particularly in Khyber Pakhtunkhwa and Balochistan provinces.

Pashto has a rich oral and written literary tradition, with its own script derived from the Arabic alphabet, adapted to accommodate the specific sounds of the language. The script includes unique letters and diacritical marks not found in Arabic. Pashto has several dialects, which can be broadly divided into Northern, Southern, and Western varieties, each with distinct phonological and lexical features.

The grammar of Pashto is characterised by its use of gendered nouns, verb conjugation based on tense, aspect, and mood, and a subject-object-verb (SOV) word order. Pashto also has a complex system of inflection and a rich vocabulary influenced by Persian, Arabic, and other regional languages.

Efforts to promote and preserve Pashto include its use in education, media, and government. Pashto literature, both classical and contemporary, plays a significant role in the cultural identity of the Pashtun people, with poetry being particularly esteemed. Despite the challenges posed by conflict and political instability in the region, Pashto remains a vibrant and essential component of Afghan cultural heritage.