Grimm's Law

Grimm’s Law describes how the sounds of certain consonants changed as the Germanic languages evolved from earlier Indo-European languages. Essentially, it shows a pattern where specific consonant sounds shifted: voiceless stops like /p/, /t/, /k/ changed to fricatives /f/, /θ/ (as in "th"), and /h/; voiced stops /b/, /d/, /g/ became their voiced fricatives /β/, /ð/, /ɣ/; and the voiced aspirated sounds turned into plain voiced stops. These systematic changes helped linguists trace relationships between languages such as English, German, and Latin, by revealing common ancestral sounds.