Consider the case of RSS vs Twitter. When Twitter came along it grew fast, it overtook RSS. It didn't do away with RSS, because it's still here co-existing with Twitter. It still has advantages over Twitter. Richer data. Extensibility. Podcasting. Titles. Styling. Multiple links per item. No character limit. If RSS has so much going for it, why did Twitter surpass it? Not for any of the reasons Johannes cites. Imho it was because subscribing was done with a single click. That could have been done with RSS too, in fact we had it working in our own RSS network at UserLand, we called it the coffee mug. One click to subscribe. it could have become a universal one-click subscribe, if our competitors were willing to go along with UserLand's leadership, but they weren't. One click to subscribe was an important survival trait in the Darwinian ecosystem of online social nets. Twitter had it, RSS didn't.#