On December 9, 1968, Doug Englebart put a ding in the universe. Over 90 minutes, he and his colleagues at Stanford Research Institute demonstrated an innovative collaborative computing environment to an audience at the Fall Joint Computer Conference in San Francisco. This visionary system pioneered many of the critical conceptual models and interaction mechanisms we take for granted in today’s personal computers: interactive manipulation of onscreen text, sharing files remotely, hypermedia, the mouse, windows, and more. It blew everybody’s mind.

Apple’s Macintosh — introduced in 1984 — was the first computing system to bring the innovations pioneered by Mr. Englbart and his team to the masses. Macs were initially dismissed as “toys” — everybody who was a serious computer user knew that terminal commands were the way to go. Until they weren’t, and windows-based UIs became the norm. It took about a decade after the Mac’s introduction for the paradigm to take over. Roughly a quarter of a century after The Demo, it’d become clear that’s how computers were to be used.

We’re now in the midst another paradigm shift in how we interact with computers. Most computer users today don’t work in WIMP environments. Instead of the indirect mouse-pointer interaction mechanism, people now interact with information directly through touchscreens. Instead of tethered devices propped atop tables, most computers today are small glass rectangles we use in all sorts of contexts.

Still, fifty years on The Demo resonates. The underlying idea of computing as something that creates a collaborative information environment (instead of happening as a transactional user-machine interaction) is still very much at the core of today’s paradigm. Every time you meet with a friend over FaceTime or write a Google Doc with a colleague, you’re experiencing this incredibly powerful vision that was first tangibly articulated half a century ago.

A website — The Demo @ 50 — is celebrating Mr. Englebart’s pioneering work in this milestone anniversary. The site is highlighting events in Silicon Valley and Japan to commemorate The Mother of all Demos. If you aren’t in either location, there are several online activities you can participate in at your leisure. If you join online, you’ll be able to commemorate The Demo in a most meta way: by doing so in the type of interactive information environments presaged by The Demo itself.