Following Joshua Fishman’s definition, diglossia is a stable situation in which two language varieties coexist in the same society and each has a specific social function. In Algeria, this situation appears clearly between Modern Standard Arabic and Algerian Arabic (Darija). Modern Standard Arabic is the High (H) variety because it is used in formal contexts such as education, government, official documents, media, and religious discourse, and it has high prestige. On the other hand, Darija is the Low (L) variety, used in everyday communication, family life, and informal situations; it is the mother tongue of most Algerians but is rarely used in formal writing. In addition, the presence of Tamazight and the wide use of French in administration and higher education make Algeria’s linguistic situation more complex, creating a form of extended diglossia within a multilingual society.