IMDB: Rating Scale/ User Reviews/ Personalized profile/ Newsfeed

Instagram: Photo posting/ Profile editing/ Advertising/ Scrolling/ Video content

YouTube: Video content/ Like, dislike buttons/ Comments/ Subscribers/ Personalized recommendations

Reddit: socially curated content/ promoted by site members/ voting

Facebook: Friends/ Posts/ Status updates/ groups/ minigames

X: Tweeting/ direct messaging/ newsfeed