The “colloquial” spoken varieties of Arabic are learned at home and constitute the native languages of Arabic speakers. “Formal” Literary Arabic (usually specifically Modern Standard Arabic) is learned at school; although many speakers have a native-like command of the language, it is technically not the native language of any speakers. Both varieties can be both written and spoken, although the colloquial varieties are rarely written down, and the formal variety is spoken mostly in formal circumstances, e.g., in radio broadcasts, formal lectures, parliamentary discussions, and to some extent between speakers of different colloquial varieties. Even when the literary language is spoken, however, it is normally only spoken in its pure form when reading a prepared text out loud. When speaking extemporaneously (i.e. making up the language on the spot, as in a normal discussion among people), speakers tend to deviate somewhat from the strict literary language in the direction of the colloquial varieties. In fact, there is a continuous range of “in-between” spoken varieties: from nearly pure Modern Standard Arabic (MSA), to a form that still uses MSA grammar and vocabulary but with significant colloquial influence, to a form of the colloquial language that imports a number of words and grammatical constructions in MSA, to a form that is close to pure colloquial but with the “rough edges” (the most noticeably “vulgar” or non-Classical aspects) smoothed out, to pure colloquial. The particular variant (or register) used depends on the social class and education level of the speakers involved, and the level of formality of the speech situation. Often it will vary within a single encounter, e.g., moving from nearly pure MSA to a more mixed language in the process of a radio interview, as the interviewee becomes more comfortable with the interviewer. This type of variation is characteristic of the diglossia that exists throughout the Arabic-speaking world.