The electron is a fundamental constituent of all matter. The electron surrounds the nucleus of an atom. The electron also has a significant influence on the nature of the atom, and therefore, a significant influence on everything that exists.
The electron can transition from one atom to another, and as it does, changes some of the characteristics of the atom. This exchange is called the electron flow, as it moves from the negative to the positive, through liquid, gas, or vacuum.
Polarity, negative to positive guarantees that electrons will always flow in the same direction. This is called Direct Current. Or DC.
Electrons flowing from negative to positive has the effect of creating more stimulation on the positive side, because it is the destination of that flow.
If you pour out a pitcher of water onto the floor, there will very little commotion at the spout, where the water comes out, but lots of chaos everywhere it lands. On Model A, this lead is always marked in RED.