Ethereum is a blockchain-based, decentralized computing platform that allows running smart contracts. This book provides a basic overview of how Ethereum works, its ecosystem, mining process, and the consensus mechanism. It also demonstrates a step-by-step approach for building decentralized applications. This book begins with the very basics of Blockchain technology. Then it dives deep into the Ethereum architecture, framework and tools in its ecosystem. It also provides you an overview of ongoing research on Ethereum, for example, Layer 1 and 2 scaling solution, Stablecoin, ICO/STO/IEO, etc. Next, it explains Solidity language in detail, and provides step-by-step instructions for designing, developing, testing, deploying, and monitoring decentralized applications. In addition, you’ll learn how to use Truffle, Remix, Infura, Metamask, and many other Ethereum technologies. It’ll also help you develop your own cryptocurrency by creating ERC20, and ERC721 smart contracts from scratch. Finally, we explain private blockchains, and you learn how to interact with smart contracts through wallets.