In common parlance, "guttural R" is the phenomenon whereby a rhotic consonant (an "R-like" sound) is produced in the back of the vocal tract (usually with the uvula) rather than in the front portion thereof and thus as a guttural consonant. Speakers of languages with guttural R typically regard guttural and coronal rhotics to be alternative pronunciations of the same phoneme, despite articulatory differences. Similar consonants are found in other parts of the world, but they often have little to no cultural association or interchangeability with coronal rhotics (such as [r], [ɾ], and [ɹ]) and are (perhaps) not rhotics at all.
The guttural realization of a lone rhotic consonant is typical in most of what is now France, French & Flemish-speaking Belgium, most of Germany, Denmark, the southern parts of Sweden and southwestern parts of Norway; it is also frequent in the Netherlands, and among all French- and some German speakers in Switzerland and also in eastern Austria, including Vienna. German speakers who use the frontal-R mainly live in the Alps or closeby.