The largest differences between classical and colloquial Arabic are the loss of morphological markings of grammatical case; changes in word order, an overall shift towards a more analytic morphosyntax, the loss of the previous system of grammatical mood, along with the evolution of a new system; the loss of the inflected passive voice, except in a few relict varieties; restriction in the use of the dual number and (for most varieties) the loss of the feminine plural. Many Arabic dialects, Maghrebi Arabic in particular also have significant vowel shifts and unusual consonant clusters. Unlike other dialects, in Maghrebi Arabic first person singular verbs begin with a n- (ن). This phenomenon can also be found in the Maltese language, which itself emerged from Sicilian Arabic.
The identity of the oldest Arabic grammarian is disputed; some sources state that it was Abu al-Aswad al-Du’ali, who established diacritical marks and vowels for Arabic in the mid-600s, Others have said that the earliest grammarian would have been Ibn Abi Ishaq (died AD 735/6, AH 117).
The schools of Basra and Kufa further developed grammatical rules in the late 8th century with the rapid rise of Islam. From the school of Basra, generally regarded as being founded by Abu Amr ibn al-Ala, two representatives laid important foundations for the field: Al-Khalil ibn Ahmad al-Farahidi authored the first Arabic dictionary and book of Arabic prosody, and his student Sibawayh authored the first book on theories of Arabic grammar. From the school of Kufa, Al-Ru’asi is universally acknowledged as the founder, though his own writings are considered lost, with most of the school’s development undertaken by later authors. The efforts of al-Farahidi and Sibawayh consolidated Basra’s reputation as the analytic school of grammar, while the Kufan school was regarded as the guardian of Arabic poetry and Arab culture. The differences were polarizing in some cases, with early Muslim scholar Muhammad ibn `Isa at-Tirmidhi favoring the Kufan school due to its concern with poetry as a primary source.
Early Arabic grammars were more or less lists of rules, without the detailed explanations which would be added in later centuries. The earliest schools were different not only in some of their views on grammatical disputes, but also their emphasis. The school of Kufa excelled in Arabic poetry and exegesis of the Qur’an, in addition to Islamic law and Arab genealogy. The more rationalist school of Basra, on the other hand, focused more on the formal study of grammar.