The history of social media in 5 waves:

1st wave: Focus on protocols. Examples: Email, finger, Usenet, BBS, listserv, IRC

2nd wave: Focus on web. Examples: Classmates.com, LiveJournal, Habbo, Friendster

3rd wave: Focus on browser-based apps. Examples: MySpace, Facebook, YouTube, Flickr, Reddit

4th wave: Focus on mobile apps. Examples: Twitter, Instagram, Snapchat, TikTok

5th wave: Focus on decentralization. Examples: Mastodon, Bluesky, Matrix, Pixelfed, PeerTube