Electric charge has three fundamental properties: (1) Quantization — charge exists in discrete packets q = ne where n is an integer and e = 1.6 x 10^(-19) C; (2) Conservation — total charge in an isolated system remains constant; (3) Additivity — charges add algebraically like scalars. Charge is a scalar quantity with SI unit coulomb (C) and dimensional formula [A T]. Protons carry +e, electrons carry -e. Charging methods: friction, conduction, and induction. In induction, a charged body induces opposite charge on the near side and same charge on the far side of a conductor — grounding allows charge separation without direct contact.