When I type the following command in the Terminal:
xdpyinfo | grep dimensions
I get the following output:
dimensions: 1366x768 pixels (361x203 millimeters)
As far as I know these are the number of pixels that my monitor has along the horizontal and vertical axis respectively.
Here is my doubt: When I am on Youtube and I am watching a video with a 720p resolution I understand the fact that my monitor can handle it since 720p<768p.
However if I play the video at a higher resolution, for example 1080p, I can't understand how it is possible to actually appreciate the better quality of the video if my monitor has less pixels than the resolution I have selected (768p<1080p).
Hopefully the question makes sense.