Short answers, pulled from the story.
The Germanic languages began to develop distinct sound changes in the middle of the 1st millennium BC through a systematic rearrangement of consonants known as Grimm's Law. This linguistic event transformed Proto-Indo-European consonants into unique Germanic sounds such as 'p' becoming 'f' and 't' becoming 's' or 'th'. These consistent changes allowed linguists to reconstruct the history of the family tree from them.
The Germanic languages were originally spoken in the Iron Age regions of modern-day Scandinavia, Northern Germany, and along the coasts of the North and Baltic Seas. Proto-Germanic was the common ancestor spoken by tribes who eventually migrated southward to settle in the area of today's western Germany and along the Baltic coasts by the 2nd century BC.
Crimean Gothic survived the longest after the East Germanic branch disappeared, lingering on until the late 18th century in isolated areas of Crimea. The Goths, Burgundians, and Vandals became linguistically assimilated by their neighbors by the 7th century, leaving Crimean Gothic as the final remnant of the East Germanic group.
Germanic languages are distinguished by the reduction of Indo-European tense and aspect combinations into only the present tense and the past tense. They also feature a strong stress on the first syllable of the word which triggered phonological reduction of other syllables and the development of weak verbs using a dental suffix instead of vowel alternation.
Today, the Germanic languages are spoken natively by a population of about 515 million people, mainly in Europe, Northern America, Oceania, and Southern Africa. English is the most widely spoken Germanic language with an estimated 2 billion speakers and serves as an official language in countries such as Belize, Canada, Nigeria, and the United Kingdom.
The earliest written evidence of the Germanic languages appears on the Negau helmet dated to the 2nd century BC which bears an inscription in Old Italic script. The earliest coherent Germanic text preserved is the 4th-century Gothic translation of the New Testament by Ulfilas, a bishop who developed the Gothic alphabet specifically for this purpose.