Originally Posted by Matt 26z

First of all you have to take into consideration who was big before MySpace. It all started with the dating sites, and then FaceTheJury did a spinoff of that and it appealed greatly to a younger audience. Then people wanted a place that allowed them to say more and have greater human interaction, so LiveJournal exploded. Then they used PhotoBucket to put stuff on LJ. These three services were usually used simultaneously.

Then along came MySpace, and they offered all of this in a single website. That's it right there. They found the sites people like and combined them. They are still doing it. When YouTube took off, MySpace quickly added video support so they wouldn't lose anyone.