High German consonant shift

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.

Source: Wikipedia — High German consonant shift (CC BY-SA 4.0)