
Even before the arrival of the touch screen there was someone who insisted on touching the screen with his finger to indicate something. Thanks to the introduction of resistive screens and capacitive screens later, there are more people who dare touch screens without taking into account the risks that may be required.
However, in the normal screens we find in the market, we do not have this crystal protection, and we have a "bare" LCD panel, where if we press the finger we will put pressure on the liquid crystal of the screen, and that is why we see this place where we press it becomes darker.
May not have to press once the screen negative effects in the short term. If you do this with the nail, you can tear off the protective film or leave a mark on the screen. It is also possible to break some pixels and the screen remains specific at that point. In the long run this effect is worse. If we touch the screen continuously, we will find an increasingly dirty screen with uneven lighting, which can also be generated in case of excessive finger pressure on the screen.
May not have to press once the screen negative effects in the short term. If you do this with the nail, you can tear off the protective film or leave a mark on the screen. It is also possible to break some pixels and the screen remains specific at that point. In the long run this effect is worse. If we touch the screen continuously, we will find an increasingly dirty screen with uneven lighting, which can also be generated in case of excessive finger pressure on the screen.

This also applies to cleaning the screen, as you never have to press hard (even when there are stains), never use abrasive or corrosive materials, and not just wet fabrics without wetting the screen. So, if you have fingerprints for people on your screen, just use water and a clean cloth to clean it smoothly and leave it clean.