As we discussed in the previous section, Ethereum is a platform for decentralized applications. That means that we can write programs that can execute in a decentralized manner, where there is no central server or central entity that is going to execute our programs. The programs are going to be executed on many different computers, and this means that there is no way to take down such a decentralized application. In order to write such applications, we need to develop smart contracts, and smart contracts are written in a programming language called solidity. So, on the Ethereum blockchain, if you want to write a smart contract you need to learn solidity. Solidity is Turing complete. So, what does that mean? To understand this, we need to go back 60 or 70 years.
During that time, people had different calculation machines. The problem was that if you had a machine that could calculate something using one algorithm, then that machine could solve only...