Varieties of Arabic
There are many varieties of Arabic (also called dialects of Arabic or vernacular languages) in existence. Arabic is a Semitic language within the Afroasiatic family that originated on the Arabian Peninsula. It is classified as a macrolanguage comprising 30 modern varieties, including its standard form. The largest divisions occur between the spoken languages of different regions. Some varieties of Arabic in North Africa, for example, are not easily comprehensible to an Arabic speaker from the Levant or the Persian Gulf. Within these broad regions further and considerable geographic distinctions exist, within countries, across country borders, even between cities and villages.
Dual (grammatical number)
Among living languages, Modern Standard Arabic has a mandatory dual number, marked on nouns, verbs, adjectives and pronouns. (First-person dual forms, however, do not exist; compare this to the lack of third-person dual forms in the old Germanic languages.) Many of the spoken Arabic dialects have a dual marking for nouns (only), and its use can be mandatory in some dialects, and not mandatory in others. Likewise, Akkadian had a dual number, though its use was confined to standard phrases like "two hands", "two eyes", and "two arms". The dual in Hebrew has also atrophied, generally being used for only time, number, and natural pairs even in its most ancient form.