Short answers, pulled from the story.
Makoto Shinkai created the first original net animation in 1997. He produced his earliest animated short films on a home computer and distributed them directly on the Internet, bypassing traditional distribution channels entirely.
Makoto Shinkai released his work Tōi Sekai in 1997. This title marked the beginning of a new era where animation could exist without a physical medium.
The Japanese anime industry began broadcasting ONA web series on the Internet in the early 2000s. Early examples of ONA series include Infinite Ryvius: Illusion in 2000, Ajimu in 2001, and Mahou Yuugi in 2001.
Full series began to be licensed exclusively for streaming services like Netflix, Amazon Prime Video, and Disney+ in the second half of the 2010s. This marked a significant shift in the way anime was distributed and consumed.
Original net animations can be viewed on television, mobile devices or computers. This versatility has allowed ONAs to reach a global audience, transcending the boundaries of traditional media.