The fact that any observable charge is an integral multiple of the elementary charge $e$ is known as

1. Every charge is transferred as whole electrons, so $q = ne$ with $n = \pm 1, \pm 2, \ldots$ and $e = 1.6\times10^{-19}$ C. 2. Charge cannot exist as a fraction of $e$; this is **quantisation of charge**. 3. Conservation refers to total charge being constant; superposition is about adding forces/fields. _Source: Samacheer Kalvi Class 12 Physics Vol.1, Unit 1 'Electrostatics', §1.1.2 (iii)_