Benrath line in the context of "Uerdingen line"

German dialects are the various traditional local varieties of the German language. Though varied by region, those of the southern half of Germany beneath the Benrath line are dominated by the geographical spread of the High German consonant shift, and the dialect continuum that connects High German to the neighboring varieties of Low Franconian (Dutch) and Low German.

The varieties of German are conventionally grouped into Upper German, Central German and Low German; Upper and Central German form the High German subgroup. Standard German is a standardized form of High German, developed in the early modern period based on a combination of Central German and Upper German varieties.

Low German is a West Germanic language spoken mainly in Northern Germany and the northeastern Netherlands. The dialect of Plautdietsch is also spoken in the Russian Mennonite diaspora worldwide. "Low" refers to the altitude of the areas where it is typically spoken.

Low German is most closely related to Frisian and English, with which it forms the North Sea Germanic group of the West Germanic languages. Like Dutch, it has historically been spoken north of the Benrath and Uerdingen isoglosses, while forms of High German (of which Standard German is a standardized example) have historically been spoken south of those lines. Like Frisian, English, Dutch and the North Germanic languages, Low German has not undergone the High German consonant shift, as opposed to Standard High German, which is based on High German dialects. Low German evolved from Old Saxon (Old Low German), which is most closely related to Old Frisian and Old English (Anglo-Saxon).

Ripuarian (/ˌrɪpjuˈɛəriən/ RIP-yoo-AIR-ee-ən) or Ripuarian Franconian is a German dialect group, part of the West Central German language group.Together with the Moselle Franconian which includes the Luxembourgish language, Ripuarian belongs to the larger Central Franconian dialect family and also to the linguistic continuum with the Low Franconian languages.

It is spoken in the Rhineland south of the Benrath line — from northwest of Düsseldorf and Cologne to Aachen in the west and to Waldbröl in the east.

The High German languages (German: hochdeutsche Mundarten, i.e. High German dialects), or simply High German (Hochdeutsch [ˈhoːxˌdɔɪ̯t͡ʃ] ) – not to be confused with Standard High German which is commonly also called "High German" – comprise the varieties of German spoken south of the Benrath and Uerdingen isoglosses, i.e., in central and southern Germany, Austria, Liechtenstein, Switzerland, Luxembourg, and eastern Belgium, as well as in neighbouring portions of France (Alsace and northern Lorraine), Italy (South Tyrol), the Czech Republic (Bohemia), and Poland (Upper Silesia). They are also spoken in diasporas in Romania, Russia, Canada, the United States, Brazil, Argentina, Mexico, Chile, and Namibia.

High German is marked by the High German consonant shift, separating it from Low German (Low Saxon) and Low Franconian (including Dutch) within the continental West Germanic dialect continuum. "Low" and "high" refer to the lowland and highland geographies typically found in the two areas.

In historical linguistics, the High German consonant shift or second Germanic consonant shift is a phonological development (sound change) that took place in the southern parts of the West Germanic dialect continuum. The shift is used to distinguish High German from other continental West Germanic languages, namely Low Franconian (including standard Dutch) and Low German, which experienced no shift. The shift resulted in the affrication or spirantization of the West Germanic voiceless stop consonants /t/, /p/, and /k/, depending on position in a word. A related change, the devoicing of the voiced stopped consonants /d/, /b/ and /ɡ/, was less widespread, and only the devoicing of /d/ is found in most dialects.

There is no consensus on when the High German consonant shift occurred; it probably began between the 3rd and 5th centuries and was complete before the first written examples in Old High German, the earliest recorded stage of High German, were produced in the 8th century. There is also no consensus on where or how the shift proceeded.

An isogloss, also called a heterogloss, is the geographic boundary of a certain linguistic feature, such as the pronunciation of a vowel, the meaning of a word, or the use of some morphological or syntactic feature. Isoglosses are a subject of study in dialectology, in which they demarcate the differences between regional dialects of a language; in areal linguistics, in which they represent the extent of borrowing of features between languages in contact with one another; and in the wave model of historical linguistics, in which they indicate the similarities and differences between members of a language family.

Major dialects are typically demarcated by bundles of isoglosses, such as the Benrath line that distinguishes High German from the other West Germanic languages and the La Spezia–Rimini Line that divides the Northern Italian languages and Romance languages west of Italy from Central Italian dialects and Romance languages east of Italy. However, an individual isogloss may or may not have any coterminus with a language border. For example, the front-rounding of /y/ cuts across France and Germany, while the /y/ is absent from Italian and Spanish words that are cognates with the /y/-containing French words.