What makes Facebook successful is exactly the same as what makes HackerNews successful. It is a combination of the illusion of social recognition (getting liked

What makes Facebook successful is exactly the same as what makes HackerNews successful. It is a combination of the illusion of social recognition (getting liked/upvoted) and a variable reward schedule (you never know if there is something new) that makes people type news.ycombinator.com or facebook.com in their address bar whenever they have free time. What you are naming are just features that make Facebook a good tool, but it does not explain why Facebook is so addictive. It of cause also has everything to do with the network effect. Now if you want to know why Facebook got successful originally that has everything to do with spreading from a small, but well-connected, influential group. Disclaimer: I used to work for a major European social network, so I know at least partially what I am talking about. EDIT: Also, making a social network scale is much more difficult then you would think. That is why Friendster failed and this is also part of the reason why we (hyves.nl) failed. Our site was notorious for being slow and when we finally got the problem under control, we already had a bad reputation with the in-crowd. Facebook had both an excellent technical team and the advantage of starting of in a half-open beta.