[DonHopkins]

Here's how Jim Fulton (who wrote the early graphics drivers for X6) explains it:

https://www.quora.com/profile/Jim-Fulton

https://www.quora.com/Why-is-the-X-Windows-architecture-clie...

>Given it's roots, X naturally used the technically-correct terms to describe its major components: the portion that abstracted display and input hardware into a service that could be used by other programs was called the "display server"; the portion that made use of those services was called the "display client." This later caused endless confusion who thought that "server" was a synonym for "big computer" (file server, database server, etc.) and "client" meant "small computer" (diskless client, etc.). Who knows, maybe it would have been easier had they been called "application server" and "application client" but that revisionist history.

Also interesting:

>Ultimately, the pendulum swung back with the advent of Web 2.0 technology and mobile devices. Now, we take it for granted that applications can run anywhere in the network and be accessed by any type of device. While X is primitive compared to JavaScript and HTML5 (whose ability to push computational tasks over the network into the display device were inspired by Java and NeWS), X did lay the initial groundwork. It also proved that an open source model could work for in business environments. Not too shabby for a technology that will soon be hitting its 30th anniversary.

>Jim Fulton, alumnus of Project Athena, the MIT X Consortium, Cognition (first commercial use of X on DOS) and Network Computing Devices (leading X terminal vendor)