?Diglossia Diglossia is generally defined as a situation in which two languages (or two varieties of the same language) are used under different conditions within a community, often by the same speakers. In sociolinguistics, it is a situation in which two distinct varieties of a language are spoken within the same speech community. Concerning the classic diglossic situation (the narrow sense of diglossia), two varieties of a language, such as standard Arabic and Colloquial Arabic, exist alongside each other in a single society. Each variety has its own fixed functions--one a 'high,' prestigious variety, and one a 'low,' or colloquial, one. Using the wrong variety in the wrong situation would be socially inappropriate. Accordingly, Ralph Fasold states that: "A very significant aspect of diglossia is the different patterns of language acquisition associated with the High [H] and Low [L] dialects...Most reasonably well-educated people in diglossic communities can recite the rules of H grammar, but not the rules for L. On the other hand, they unconsciously apply the grammatical rules of L in their normal speech with near perfection, whereas the corresponding ability in H is limited." The Sociolinguistics of Society Since diglossia is a remarkable phenomenon in Arabic, hereinafter it would be applied on four various levels in both High and Low Arabic varieties, as follows: -Phonological Diglossia: -The word ‘ox’, the initial sound is /?/ in (???) High Arabic Variety HAV, changes to be /t/ in (???) Low Arabic Variety LAV. -The word ‘glasses’, the mid sound is /?/ (??????) in HAV, changes to be/d/ in (??????) in LAV. Also /?/ in (???) HAV, changes to be /d/ in (???) LAV. -Morphological Diglossia: - the word ‘half’ in HAV is (???) but in LAV is (??). -Syntactic Diglossia: - ‘Ahmed did not go out’; in HAV it is (?? ???? ????) but in LAV it is (???? ?????). -lexical Diglossia which is divided into: 1-Pairs of words: - The w