What is quantization of charge ? What is the reason of quantization ?

Explanation

All the charges found in nature are integral multiples of a basic unit of charge denoted by e. "This fact is called Quantisation".
Thus charge q on a body is always given by q = ne where n is positive or negative integer.
The quantisation of charge was first suggested by the experimental laws of electrolysis discovered by English experimentalist Faraday. It was experimentally demonstrated by Millikan in 1912.
The main reason of quantisation is that when two bodies are rubbed, only integer no. of electrons are transferred from one body to another.