Why is it possible to flip the screen? [closed]

Solution 1:

One common case where you'd want to turn your screen upside down is if you have a laptop doubling as a tablet computer, like this:

Another common case is if you attach a projector to the ceiling instead of letting it stand on a table, or using a rotated (and thus portrait) monitor.

Solution 2:

Addressing the sideways rotation part of the question, the main time I've done so is when I've wanted to see many lines of content at once, e.g. a long file of code, a terminal output, or a spreadsheet. Some desktop monitors (e.g. this one) have a stand that rotates by 90°, but the software needs to rotate the video output too, otherwise everything becomes harder to read.

Solution 3:

One can envision a circumstance in which the display mounting and associated brackets can only permit an inverted attachment of the panel. A kiosk with limited access may be one example, a display unit mounted at ceiling height with a mounting bracket that cannot be attached unless upside down.

In the case of a laptop, I can picture a situation in which the keyboard is mounted inside a box with the display extending outside the enclosure which would require to invert the image for viewing in a normal orientation.

I expect there are other circumstances in which this applies.