Classical Arabic or Quranic Arabic (al-ʿarabīyah l-fuṣḥā) is the standardized literary form of Arabic used from the 7th century and throughout the Middle Ages, most notably in Umayyad and Abbasid literary texts such as poetry, elevated prose and oratory, and is also the liturgical language of Islam. Classical Arabic is, furthermore, the register of the Arabic language on which Modern Standard Arabic is based.
A comprehensive written grammar of Classical Arabic was by the Persian Muslim grammarian Sibawayh; it was an exegesis of Arabic grammar largely based on the existing poetic texts and the works of previous grammarians, in addition to the Qur'an and Bedouin informants whom he considered to be reliable speakers of Arabic. The primary focus of this work was to facilitate tafsir of the Qur'an and prophetic reports.
Modern Standard Arabic is its direct descendant used today throughout the Arab world in writing and in formal speaking, for example prepared speeches, some radio and TV broadcasts and non-entertainment content. Whilst the lexis and stylistics of Modern Standard Arabic are different from Classical Arabic, the morphology and syntax have remained basically unchanged (though Modern Standard Arabic uses a subset of the syntactic structures available in Classical Arabic). In the Arab world little distinction is made between Classical Arabic and Modern Standard Arabic and both are normally called (الفصحى) in Arabic, meaning 'the most eloquent'.
The earliest forms of Arabic are known as Old Arabic and survive in inscriptions in Ancient North Arabian scripts as well as fragments of pre-Islamic poetry preserved in the classical literature. By the late 6th century AD, it is hypothesized that a relatively uniform intertribal "poetic koiné", a synthetic language distinct from the spoken vernaculars, had developed with conservative, as well as innovative, features, including the case endings known as ʾiʿrab.