Friendster

Friendster was one of the first big social networks to make profiles, visible friend connections, and online status feel like the whole internet game.

It helped teach people the mechanics of online identity, popularity, and very visible friend drama before those things hardened into the rules of modern social media. In a lot of ways, it was the rough draft for how people would later live online.

Performance issues, scaling problems, and aggressive competition made it hard for Friendster to hold onto its early lead.

What makes it important is that it proved social networking could become a mass obsession before the eventual winners fully showed up.