Subreddit
Themed forum section on Reddit. Prefix r/. Own mod team, rules, culture. r/AskHistorians (strictly academic), r/aww (cat pictures), r/programming (tech news). Number of active subs: 130,000+.
Created by users; moderated for free by volunteers. 2023 crash: Reddit API price hike led to a protest where thousands of subs went dark. Result: some moved to Lemmy/Discord, but Reddit's network effect kept the traffic. Standard reservoir for "what's the consensus on X?" — Google trick: "[question] reddit". LLM training data is largely Reddit dumps. Own terminology: OP (Original Poster), TL;DR, AMA (Ask Me Anything), ELI5 (Explain Like I'm 5).