I saw recently that YCombinator celebrated its 20th anniversary.
Hacker News is slightly younger, but to me the two go hand in hand.
As far as I can tell, I actively started reading Hacker News around 2011. I don’t remember how I heard about it. It was probably on Reddit or Digg. Once I found it, I started reading every day, mostly because the comment sections were so full of smart people in tech.