How is Plattdeutsch related to Dutch, Frisian, and English?

Plattdeutsch, also known as Low German, is a member of the West Germanic language family, which also includes English, Frisian, and Dutch.1

These languages share a common ancestry and historical development:

• Relationship to English and Frisian: Historically, Old Saxon—the earliest form of Low German—shared a distinctive preservation of voiceless stops (p, t, k) with Old Frisian and Old English, distinguishing them from High German, which underwent a consonant shift. Additionally, Frisian and English share specific linguistic features, such as the loss of certain nasal sounds and the palatalization of specific consonants, that differentiate them from other Germanic languages.23
• Relationship to Dutch: The territory spanning from the Netherlands to Germany forms a dialect continuum where local speech transitions gradually rather than abruptly. Low German dialects in the northeastern Netherlands share affinities with those in northern Germany. Furthermore, Dutch itself evolved from Low Franconian, which is closely related to the linguistic strains that developed into modern Low German dialects.456

While these languages are related, they have diverged significantly over time due to different historical, political, and linguistic influences.17