PIE the largest and most diverse offshoot from ProtoWorld. As there are a lot of people who don't know linguistics, I was being very facetious there. "ProtoWorld," the idea that all language share an ancestor, is a very naive theory that has next to no supporting evidence. And IndoEuropean languages are certainly not the most diverse language family even though they might be the most widely spoken, both in terms of area and population. This description is falling apart. Okay

Sources:
https://alic.sites.unlv.edu/chapter1...
https://lrc.la.utexas.edu/books/piep/...
https://ahdictionary.com/word/indoeur...
https://www.ling.upenn.edu/~kroch/cou...
https://www.ling.upenn.edu/~rnoyer/co...
https://gucorpling.org/amir/IE_Glossa...

0:00 Introduction
0:41 Phonology
4:10 Vowels and Ablaut
5:42 Ablaut example
6:52 Roots vs. Words
7:22 Lexemes vs. Words
7:57 Verb Inflection
9:16 Noun Inflection
11:31 Example Sentence