The X Window System didn’t immediately have X terminals

For a while, X terminals were a reasonably popular way to give people comparatively inexpensive X desktops. These X terminals relied on X's network transparency so that only the X server had to run on the X terminal itself, with all of your terminal windows and other programs running on a server somewhere and just displaying on the X terminal. For a long time, using a big server and a lab full of X terminals was significantly cheaper than setting up a lab full of actual workstations (until inexpensive and capable PCs showed up). Given that X started with network transparency and X terminals are so obvious, you might be surprised to find out that X didn't start with them.

Chris Siebenmann

I did indeed assume X terminals were part of the ecosystem from day one, but it makes sense that it took a while, and that they didn't enter the scene until X had established itself as the standard windowing system in the UNIX world. I've been trying to get my hands on specifically the last HP X terminal, but they're hard to find and often very expensive. I'd love to get a taste of a proper networked X environment on real UNIX, in the way people actually used to use it professionally.

As a sidenote, Siebenmann is doing such an excellent job with these stories about UNIX, X11, and related matters. He's like the Raymond Chen of the UNIX world.