A capacitive touchscreen expects your finger to change the electrical conditions near its sensor grid. Bare skin conducts well enough for the screen to detect this change. Many ordinary gloves are electrical insulators. They separate your finger from the screen and reduce the change in capacitance until it becomes too small for the phone to recognise. Touchscreen-compatible gloves include conductive material in the fingertips, allowing your finger's electrical effect to reach the sensor more effectively. This is why pressing harder often does not solve the problem: the screen is mainly sensing an electrical change, not mechanical pressure.

The useful part of this physics is that it helps people predict and design real things. Engineers often begin with the same simplified model used in school, test where it works, then add more detail when measurements show that the real situation is more complicated.

At the microscopic level, the important particles are electrons. Moving electrons from one material to another leaves an imbalance of charge, and charged objects create electric fields around them. Those fields can attract or repel other charges without contact. In electronic sensors, very small changes in charge or capacitance can therefore be turned into a measurable electrical signal.