There are two principal divisions of the German language: High German, or Hochdeutsch, and Low German, or Plattdeutsch. One of the most striking differences between them is the result of a consonant shift (usually referred to as the second, or High German, sound shift) that took place before the 8th cent. A.D. in certain West Germanic dialects. This sound shift affected the southern areas, which are more elevated and hence referred to as the High German region, whereas it left untouched the Low German prevalent in the lowland regions of the North. In a broader and purely linguistic sense, the term Low German can also be extended to cover all the West Germanic languages in which the second sound shift did not take place, such as Dutch, Frisian, and English.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.