Regarding 1.: In my memory, Reddit was just as confusing to newcomers, with all their terminology. What are these words people keep mentioning here? sub, GP, OP

Regarding 1.: In my memory, Reddit was just as confusing to newcomers, with all their terminology. What are these words people keep mentioning here? sub, GP, OP, flair, gold, sidebar, ... Twitter also took me ages to understand what RT and HT and via was supposed to mean and what the difference was between retweets and replies and stars (that are now likes?)...