ALEXANDROS DOLGOV grew up questioning the limits of centralized systems, inspired by Greece’s financial turmoil and his father’s stories of post-Soviet economic collapse. Discovering Bitcoin, DeFi, and DAOs ignited his vision for a decentralized future, leading him to master Solidity as a tool for change. Holding an MSc in Blockchain and Digital Currency from the University of Nicosia and the Chartered Blockchain Analyst Certification, Alexandros has contributed to key areas of the blockchain ecosystem, including DeFi, Decentralized Identity, and Token Economics. A guest lecturer and passionate advocate, Alexandros now brings his expertise to this book, empowering readers to unlock the potential of smart contract development.

• Introduction xixChapter 1: What Is Money and a Brief History of It? 1What Is Money? 1Money as a Technology 2Medium of Exchange 3Store of Value 4Unit of Account 5The History and Evolution of Money 5Barter 6Primitive Money 7Primitive Money: Conclusion 10Modern Types of Money 10Coins 11Paper Money 11Bretton Woods Conference 12Modern Types of Money: Conclusion 12Cryptocurrencies 13Bitcoin 13Bitcoin's Monetary Properties 14Bitcoin's 'Monetary Policies' 14Ethereum and Smart Contracts 16What Are Smart Contracts? 17Tokenization of Real-World Assets 17Decentralized Autonomous Organizations 22Decentralized Exchanges 22Lending/Borrowing: Aave 23Travala 23VitaDAO 24BeerDAO 24CityDAO 24Cryptocurrencies and Smart Contracts: Conclusion 24Chapter 1 Questions 25Chapter 2: An Introduction to Ethereum's Architecture 27Basics of Ethereum 27The Blockchain Trilemma 31Smart Contracts 31The Ethereum Virtual Machine 34The Ether Coin 34The Byzantine General's Problem and Ethereum's Consensus Mechanism 35Gas Fees 36The Scaling Problem of Ethereum 38Layer 2 Solutions 40Rollups 40Validiums 42Side-Chains 42Sharding 43Danksharding 44Layer 3 Solutions 44Ethereum: Toward Finalization 44Chapter 2 Questions 45Chapter 3: Wallets, Metamask, and Block Explorers 47Understanding Wallets 48Hosted Wallets 48Advantages, Disadvantages, Best Practices, and Case Studies 48Browser Wallets 51Advantages, Disadvantages, and Case Studies 51Desktop Wallet (Full Nodes) 52Advantages and Disadvantages 53Desktop Wallet (Lightweight) 53Advantages and Disadvantages 53Mobile Wallets 54Advantages, Disadvantages, and Case Studies 54Cold Storage/Hardware Wallet 55Advantages, Disadvantages, and Best Practices 55Convert Your Old Phone into a Hardware Wallet 57Multisignature Wallets 59Hierarchical Deterministic Wallets 59Installing MetaMask 60Logging In Again with the Seed Phrase 62Changing Networks 64Engaging with Faucets 65Sending Your First Transaction 71Block Explorers 74Test Network (Testnet) Block Explorer 77Block Explorer: Transaction Anatomy 78Block Explorer: Block Anatomy 78Connecting to DApps 82Block Explorer: Anatomy of a Wallet 88Chapter 3 Questions 98Chapter 4: Remix, Data Types, Visibility, and Helloworld 101What Is Programming? 101Starting with Solidity, Remix, and HelloWorld 102Creating the HelloWorld.sol File in Remix 103SPDX-License-Identifier 106Solidity Versions and the pragma Line 107Contract HelloWorld {} 110Data Types and Variables in Solidity 111int 111uint 112string 112address 113bool 113bytes 114Function Visibility Levels 116Function Anatomy 116Visibility Levels 116View and Pure Keywords 117HelloWorld Contract 117Chapter 4 Questions 120Chapter 5: Zoomanagement 123Setting Up the ZooManagement Contract 123Structs 130Arrays 132Dynamic Arrays 134Fixed-Size Arrays 135addAnimal 137getAnimal 138Mappings 139Creating a Mapping 140Contract Importing 144Inheritance 149Single Inheritance 150Multilevel Inheritance 152Multiple Inheritance 154Hierarchical Inheritance 156Deploying and Running a Contract from Another Contract 158Chapter 5 Questions 166Chapter 6: Installing Microsoft Visual Studio Code And Foundry 169What Is Microsoft VS Code? 169Microsoft Visual Studio Code Layout 172Explorer Pane 172Search Pane 174Extensions 176Night Owl 177Polacode 179Bookmarks 179Cloak 180Solidity Juan Blanco 180Even Better TOML 180GitHub Copilot 181VS Code Keyboard Shortcuts 181Working on Different Files at the Same Time 184Mirror/Mini-Map 186Zen Mode 187VS Code Terminal 187Installing Foundry 191Installing libusb and Homebrew 192Starting a Foundry Project 196Chapter 6 Questions 202Chapter 7: Foundry Zoomanagement 205The Foundry Project Files 205Compiling a Contract 208Introduction to Anvil 211Local Smart Contract Deployment 215Using Scripting to Deploy a Contract 218Contract Interaction with Foundry 224Deploying a Smart Contract to a Test Network Through Foundry 227Chapter 7 Questions 235Chapter 8: Fundraising Contract 237Setting Up a Fundraising Contract 237Oracles 240Deploying the Price Feed Contract Through Remix 251Solidity Interfaces 254Creating Libraries 259Withdraw Function 262Resetting the Mappings 263Resetting the listOfSenders Array 264Sending ETH from a Contract 265Transfer 265Send 265Call 266Constructor 267Modifiers 269Testing the Contract by Deploying It on a Test Network 270Immutability and Constants 278Custom Errors 283Receive and Fallback Functions 284Chapter 8 Questions 285Chapter 9: Building An Erc-20 Cryptocurrency 287Introduction to ERC-20 287The Process of Creating an Ethereum Improvement Proposal 289Building an ERC-20 Token with OpenZeppelin 290Building an ERC-20 Manually 299Deploy Your ERC-20 Cryptocurrency 307Chapter 9 Questions 311Chapter 10: Borrowing and Lending Protocol 313What Is a Stablecoin? 313Types of Stablecoins 316Creating the Stablecoin 322The Stablecoin Skeleton 327Chapter 10 Questions 338Chapter 11: Building An Erc-721 Nonfungible Token 341What Is an NFT? 341Setting Up the NFT Project 343ERC-721 Contract Breakdown 347Introduction to IPFS 362Downloading, Installing, and Using IPFS 363Downloading IPFS 363Installing the Browser Extension 368Using IPFS 371OpenSea 377Creating the ERC-721 Contract 382Writing a Deployment Script and Deploying on Sepolia 384Deploying the Contract 387Chapter 11 Questions 394Chapter 12: Upgradable Smart Contracts 397Introducing Upgradable Contracts 397Preset Versatility Upgrades 398Introduction to CertiK 399Contract Succession Upgrade 405Proxy Delegated Upgrade 406Using Delegatecall 410OpenZeppelin UUPS Proxies 417Importing UUPSUpgradeable.sol 422Initializer 426Deploying the Proxy Contract 431Chapter 12 Questions 433Chapter 13: Decentralized Autonomous Organizations 435What Is a DAO? 435Exploring the Aave Protocol 439Snapshot 444Potential Voting Architectures for a DAO 447The DAO Toolkit 448Setting Up the DAO Project 448Adding the RetrievableNumber.sol Contract 451Voting Token Contract 454OpenZeppelin's Contracts Wizard 457The Governance Contract 460Timelock Contract 469Chapter 13 Questions 470Chapter 14: Introduction to Smart Contract Security 471The Importance of Smart Contract Security 471Smart Contract Auditing and Security Best Practices 472Security Techniques Used for Auditing 478Having High Confidence and Assurance That Your Smart Contract Is Safe 479Chapter 14 Questions 480Chapter 15: THE FIRST (OR One OF THE FIRST) Stepping Stones 481Uploading Projects to GitHub 481Finding a Job in the Crypto Industry 484Continuing with Solidity Education 484Appendix: Answers to Chapter Questions 487Chapter 1 What Is Money and a Brief History of It? 487Chapter 2 An Introduction to Ethereum's Architecture 491Chapter 3 Wallets, MetaMask, and Block Explorers 494Chapter 4 Remix, Data Types, Visibility, and HelloWorld 499Chapter 5 ZooManagement 502Chapter 6 Installing Microsoft Visual Studio Code and Foundry 505Chapter 7 Foundry ZooManagement 508Chapter 8 Fundraising Contract 511Chapter 9 Building an ERC-20 Cryptocurrency 515Chapter 10 Borrowing and Lending Protocol 519Chapter 11 Building an ERC-721 Nonfungible Token 522Chapter 12 Upgradable Smart Contracts 524Chapter 13 Decentralized Autonomous Organizations 528Chapter 14 Introduction to Smart Contract Security 531Index 535