For almost a decade, before LCD became the norm, screens used to be 72 or 96 DPI (Usually only found on Trinitron displays). However, now 120 and 144 DPI displays are quite common.
With the coming of Windows 7, DPI issues are more or less resolved to some degree for desktop apps, and at least the UI of OS stuff is never broken on a high DPI display.
Now we come to web pages - I had a huge argument with a friend about building a DPI independent webpage - My view was that UI elements should look the same size on various systems, and that every CSS dimension should be specified in inches rather than pixels.
I raised this topic on SO and there was general disapproval about using inches as units, which i find rather -uh- un reasonable.
I have a 144 DPI screen of only 15.4 inch size - The size of individual pixels is so small that text antialiasing and subpixel rendering is really effective, but I see lots of webpages which assume that an 8 point font is big enough to read on any system.
I believe that this is a huge annoyance and a fundamental flaw in UI design... Making assumptions about the users environment when you can actually adjust to the existing one.
It's not very different from the early webpages in the 2000s which would not display properly on 1280x1024 since they were designed for 1024x768
Another irony is that only firefox renders a 1 inch element as 1 physical inch - all the other browsers are off unless your screen DPI is 96 Obviously somewhere in the code is the value 96 hardcoded - How hard is it to replace that with a GetScreenDPI() or whatever API call?
What are your views?