Private → Can only be called from that particular contract. This is not private!!! > web3.eth.getStoragedAt(contract.address, slotsNum) Internal → Can be called from that contract and derived contracts. External → Can be called from external sources. Public → Can be called from everywhere.

This is not private!!!

A Quick Guide to Hack private variables in Solidity

if you want to understand the concept of “private”, you have to know what is storage ?

• storage

Virtual and Override

contract Parent {
    uint u;
    function Test() public virtual{
        u = 1; 
    }
}

contract Child is Parent {
    function Test() public override{
        u = 2;
    }
}