Back in 1993, when Eric Bina and I were first building Mosaic, it seemed obvious to us that users would want to annotate all text on the web – our idea was that each web page would be a launchpad for insight and debate about its own contents. So we built a feature called "group annotations" right into the browser – and it worked great – all users could comment on any page and discussions quickly ensued. Unfortunately, our implementation at that time required a server to host all the annotations, and we didn't have the time to properly build that server, which would obviously have had to scale to enormous size. And so we dropped the entire feature.