This brings us to the end of this chapter. It was a heavy chapter that focused primarily on smart contracts, the different ways to create an instance, and all the important object-oriented concepts related to them, including inheritance, polymorphism, abstraction, and encapsulation. Multiple types of inheritance can be implemented in Solidity. Simple, multiple, hierarchical, and multi-level inheritance were discussed, along with usage and implementation of abstract contracts and interfaces. It should be noted that using inheritance in Solidity, there is eventually just one contract that is deployed instead of multiple contracts. There is just one address that can be used by any contract with a parent-child hierarchy.
The next chapter will focus purely on functions within contracts. Functions are central to writing effective Solidity contracts. These are functions that help change the contract state and retrieve them. Without functions, having any meaningful smart contracts is difficult...