Core Foundations of Ethereum

Understanding Ethereum: A Blockchain Platform for Decentralized Applications Introduction to Ethereum Ethereum is a decentralized blockchain platform that extends blockchain technology beyond simple cryptocurrency transactions. While Bitcoin focuses primarily on peer-to-peer payments, Ethereum enables developers to build and deploy decentralized applications (dApps) that anyone can interact with. The platform has its own native cryptocurrency called Ether (symbol: ETH), which serves two essential purposes: it incentivizes network participants to maintain the blockchain, and it fuels transactions and computations on the platform. <extrainfo>By market capitalization, Ether is the second-largest cryptocurrency globally, after Bitcoin.</extrainfo> Ethereum is built as open-source software, meaning anyone can review, audit, and contribute to its code. This transparency is a core principle of blockchain technology and helps build trust in the system. How Ethereum Maintains Its Network: From Proof-of-Work to Proof-of-Stake Blockchains need mechanisms to decide who validates new blocks and prevents bad actors from corrupting the system. Ethereum's approach to this has evolved significantly. The Original Approach: Proof-of-Work Ethereum originally used proof-of-work (PoW), the same consensus mechanism as Bitcoin. In this system, computers called miners compete to solve complex mathematical puzzles. The first miner to solve the puzzle gets to add the next block to the blockchain and receives newly created Ether as a reward. While this system is very secure, it requires enormous amounts of computational power and electricity. The Modern Approach: Proof-of-Stake and The Merge On September 15, 2022, Ethereum underwent a major transformation called "The Merge." The network transitioned from proof-of-work to proof-of-stake (PoS). Under this new system, validators are chosen to create new blocks based on how much Ether they've committed to the network as collateral, rather than based on computational puzzle-solving ability. This change had a dramatic environmental impact: the transition reduced Ethereum's energy consumption by more than 99%. This makes Ethereum substantially more sustainable than proof-of-work systems while maintaining the same security guarantees. What Can You Build on Ethereum? The true innovation of Ethereum lies in its flexibility. The platform enables developers to build a wide variety of applications using smart contracts—programs that automatically execute according to their code and cannot be changed once deployed. Decentralized Applications (dApps) Smart contracts form the foundation of decentralized applications (dApps). These are applications where the logic runs on the blockchain rather than on a centralized server. Anyone can deploy a dApp to Ethereum, and any user can interact with it directly without needing permission from a company or intermediary. Decentralized Finance (DeFi) One of the most important categories of dApps is decentralized finance (DeFi). DeFi applications enable financial services like borrowing, lending, trading, and insurance without traditional intermediaries like banks or brokers. Because these applications run on the blockchain, they're accessible to anyone with an internet connection, 24/7, and transactions are transparent and verifiable. Tokens: Fungible and Non-Fungible Ethereum makes it easy to create new digital assets called tokens. There are two main types: Fungible tokens (like ERC-20 tokens) are interchangeable—each unit is identical to every other unit. These work like digital currencies or standardized commodities. For example, if you own 10 tokens and someone sends you 10 more, you now have 20 identical tokens. Non-fungible tokens (NFTs, like ERC-721 tokens) are unique and non-interchangeable. Each NFT has distinct properties and cannot be substituted for another. This makes NFTs useful for representing ownership of digital art, collectibles, or unique in-game items. Smart Contracts as Asset Managers Smart contracts themselves can receive, hold, and transfer assets (Ether and tokens) according to their programmed rules. For example, a smart contract could automatically distribute funds to multiple recipients when certain conditions are met. Because the contract code is immutable and transparent, everyone can verify that the contract will behave exactly as programmed. Ether, Accounts, and Addresses: The Technical Foundation To use Ethereum, you need to understand how the system manages accounts, stores value, and identifies participants on the network. Ether: The Fuel of Ethereum Ether (ETH) is generated as a reward to validators who propose new blocks in the proof-of-stake system. Ether balances are stored internally as unsigned integers measured in wei, which is the smallest unit of Ether. The conversion rate is: $$10^{18} \text{ wei} = 1 \text{ Ether}$$ This large multiplier exists because early Ethereum creators wanted to allow for very precise fractional amounts without using decimals in the code. Transaction Costs When you perform transactions on Ethereum, you pay transaction fees (also called "gas fees"). These fees have two components: Base fee: A portion that is permanently removed (burned) from circulation, which helps prevent spam and manages network demand Tip: An additional payment that goes to the validator who includes your transaction in a block, incentivizing them to prioritize your transaction Two Types of Accounts Ethereum supports two different account types, and this distinction is important for understanding how the network operates: Externally-Owned Accounts (EOAs) are accounts controlled by private keys. If you have a private key, you control the account. You can use an EOA to send transactions, receive funds, and interact with smart contracts. When you create a wallet like MetaMask, you're creating an EOA. Contract Accounts are different—they contain bytecode (the compiled smart contract code) and persistent storage (where the contract can store data). Contract accounts are not controlled by private keys. Instead, they're created by deploying smart contracts through transactions from EOAs. Once created, they exist permanently on the blockchain and execute their code when other accounts interact with them. Address Format Every account on Ethereum has an address, which is a unique identifier for that account. Ethereum addresses have a specific format: They are 20 bytes of data (160 bits) They are represented as hexadecimal strings (using characters 0-9 and A-F) They are prefixed with "0x" to indicate they're hexadecimal For example, a valid Ethereum address looks like: 0x742d35Cc6634C0532925a3b844Bc9e7595f42cbe This format is standardized across the Ethereum ecosystem, so any wallet or application will recognize and use addresses in this same way. The "0x" prefix is a common convention in programming to denote hexadecimal notation.