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You walk across a carpeted room in wool socks, reach for a brass doorknob, and snap — a blue spark jumps to your fingertips. That microscopic shock is millions of subatomic particles leaping through the air to restore electrical balance.
Electric charge is an intrinsic physical property of matter carried by subatomic particles, determining how they interact via electromagnetic forces. Protons carry a positive charge, electrons carry a negative charge, and neutrons are neutral with zero net charge.
Every object around you contains trillions of these charges — so why doesn't everything constantly shock you?

Fundamental Properties of Charge

An object is neutral not because it lacks charge, but because its total positive charges exactly equal its total negative charges. In an isolated system, charge conservation dictates that net charge cannot be created or destroyed, only transferred.
Charge is also quantized, meaning any observable net charge is an integer multiple of the fundamental charge (elementary charge) e=1.602×10−19 Ce = 1.602 \times 10^{-19}\text{ C}, obeying q=neq = ne where n∈Zn \in \mathbb{Z}.
For example, if an acrylic rod gains a net charge of q=−4.806×10−18 Cq = -4.806 \times 10^{-18}\text{ C}, you can find how many excess electrons it acquired by solving for nn:
n=q−e=−4.806×10−18 C−1.602×10−19 C/electron=30 electronsn = \frac{q}{-e} = \frac{-4.806 \times 10^{-18}\text{ C}}{-1.602 \times 10^{-19}\text{ C/electron}} = 30\text{ electrons}
The microscopic mechanism of solid-state charging relies entirely on electron mobility. Because atomic nuclei remain fixed in their solid lattice positions, charging occurs exclusively through the transfer and redistribution of valence electrons.

Charging by Friction

Charging by friction (the triboelectric effect) occurs when two neutral insulators are rubbed together. Contact forces cause the material with higher electron affinity to gain electrons (q<0q < 0), while the other loses an equal number of electrons (q>0q > 0).