What made Facebook so popular these days? Why is Myspace "dead"?

[!Shanksta-Gangsta!]

So we have all these cool websites, there YouTube, then twitter showed and then all of sudden people just shifted to Facebook. Why? What happen to make Facebook so popular? I feel like its a trend, when Myspace was all the rage people couldn't stop talking about it (during that time i wasn't into Myspace). But do you think the popularity of Facebook will die down the same way it did with Myspace? Do you think they'll just end up coming back to Myspace or some other social community site?
I dont get it, you can talk and find your friends and family the same way on Myspace. I like the fact you can find them by age, ethnicity, ect cause sometimes i couldn't remember that person's whole name. I've never had a problem with spyware or hacking on the site.