Early Web is before most netizens (remember that?) had ever heard or seen the term "blog", and much of the web was folks' "home pages" on whatever weird topic they were interested in (some were effectively "blogging", but that wasn't a term yet—"web log" might see limited use). This was the Nerd Web.
Mid-period is from the rise of "blog" to the rise of the smartphone, Google capitulating in the never-ending war on spammers and ruining itself instead, and Facebook coming about. Roughly '08 would be the end of this period. Call this the Macromedia Flash Web, perhaps.
Everything since that is the Late, or Hellscape, Web, an age dominated to an extreme degree by spam, scams, ads, astroturfing, and absolute insanity becoming normalized and spilling over into real life. This is the part that made it clear we'd have been better off never inventing any of this.
As I said it’s all arbitrary. I might pick the time around Google’s founding as the early Internet, others might pick Yahoo, others might pick anything before eternal September.
[1] - https://yenimedya.aydin.edu.tr/wp-content/uploads/2024/10/3....
The Windows Aero style existed in 2004, and somewhere around 2017, the style Frutiger Aero was invented, partly based on those styles but partly new.
Just like Vaporwave.
Some aesthetics existed in the past (like art deco), some are invented out of materials from the past (like art deco revival).