[dragonwriter]

> Every smartphone sold in America in the last four years has a far higher screen resolution than the machine on which I first browsed the internet back in the 1990s. Indeed, most of them have a higher screen resolution than the laptop on which I regularly browse the internet today!

A good point, and important to keep in mind.

> So, no, the viewports on mobile devices aren't really smaller.

Except, in the ways that they are. A 5" 4K display is still literally a smaller viewport than a 13" 1366x768 display or a 20" 1920x1080 display, and this is quite important in design.

[simoncion]

Hnnh. Everywhere I've seen the word "viewport" used, it has referred to the number of pixels on the screen, along with the aspect ratios of both the pixels, and the screen itself. I dabbled in OpenGL a long way back; this is probably where I was first introduced to the term.

I would call the concept which you are calling "viewport", "screen". e.g. "This phone has a much smaller screen than this nice desktop monitor."