Detailed Instructions

A user initiates a transaction using a cryptographic key pair. This involves creating a digital signature to prove ownership. For example, sending 0.05 ETH from address 0x742d35Cc6634C0532925a3b844Bc9e to another. The transaction includes the recipient's address, the amount, a gas fee (e.g., 50 Gwei), and a nonce (a unique sequence number).

• Sub-step 1: Use your private key to sign the transaction data, creating a unique signature.
• Sub-step 2: Broadcast the signed transaction to the peer-to-peer (P2P) network of nodes using a command like eth_sendRawTransaction.
• Sub-step 3: The transaction enters the mempool, a waiting area where pending transactions are held.

Tip: Always verify the recipient address and gas fees before signing, as transactions are irreversible.

Detailed Instructions

Network nodes, called miners (Proof of Work) or validators (Proof of Stake), collect transactions from the mempool. They compete to solve a complex cryptographic puzzle (PoW) or are randomly selected (PoS) to propose the next block. This process is the consensus mechanism, ensuring all nodes agree on a single version of the truth.

• Sub-step 1: A validator bundles pending transactions, aiming to fill a block (e.g., Ethereum targets ~15M gas per block).
• Sub-step 2: The validator performs the consensus work, such as finding a nonce that produces a valid hash below the network's target difficulty.
• Sub-step 3: The proposed block, containing the solution and transactions, is broadcast to other nodes for verification.

Tip: Consensus prevents double-spending and secures the network without a central authority.

Detailed Instructions

Receiving nodes independently validate the proposed block. They check every transaction's signature, the nonce solution, and that the block follows all protocol rules. This validation ensures immutability—once added, data cannot be altered. The block is then linked to the previous block via a cryptographic hash, forming a chain.

• Sub-step 1: Nodes re-calculate the block hash to verify the proof-of-work meets the required difficulty.
• Sub-step 2: Each transaction is checked against the sender's current balance and nonce to prevent fraud.
• Sub-step 3: Upon successful validation, the node adds the block to its local copy of the distributed ledger and propagates it further.

Tip: The longest valid chain is considered the truth, making it computationally infeasible to alter past blocks.

Detailed Instructions

A smart contract is a self-executing program stored at a specific address on the blockchain, like 0x89d24A6b4CcB1B6fAA2625f. Developers write the contract code in a language like Solidity and deploy it via a transaction, which stores the bytecode on-chain.

• Sub-step 1: Write the contract. For example, a simple vault that stores and releases funds.

solidityCopy
contract SimpleVault {
    address public owner;
    constructor() { owner = msg.sender; }
    function withdraw(uint amount) public {
        require(msg.sender == owner);
        payable(owner).transfer(amount);
    }
}

• Sub-step 2: Deploy it by sending a transaction with the compiled bytecode to the zero address. This creates the contract at a new address.
• Sub-step 3: Users interact with the contract by sending transactions to its address, triggering functions that execute autonomously based on the code.

Tip: Smart contract execution consumes gas, and its state changes are recorded permanently on the blockchain.

Detailed Instructions

First, you must understand that a blockchain is a decentralized, immutable ledger. A smart contract is self-executing code deployed on this ledger, which automatically enforces terms when predefined conditions are met. Think of it as a digital vending machine: you send a specific input (like cryptocurrency) and it reliably dispenses an output.

• Key Components to Learn:
  • Public Address: The unique identifier for a contract or wallet (e.g., 0x742d35Cc6634C0532925a3b844Bc9e90F1b6f1d8).
  • Gas: The fee paid to the network to execute a transaction.
  • Wallet: Software (like MetaMask) that holds your private keys and interacts with the blockchain.
  • ABI (Application Binary Interface): A JSON file that defines how to interact with the contract's functions.

Tip: Start on a test network like Sepolia or Goerli to experiment without spending real money.

Detailed Instructions

You'll need a wallet and a way to communicate with the blockchain. Install MetaMask as a browser extension and create a wallet, securely storing your seed phrase. Then, fund your wallet with test ETH from a faucet for the network you're using.

• Essential Tools:
  • MetaMask: For managing accounts and signing transactions.
  • Block Explorer: Like Etherscan, to look up contract addresses and transaction details.
  • Development Framework: Hardhat or Foundry for local testing and deployment.
  • Node Provider: A service like Alchemy or Infura to connect your code to the blockchain network via an RPC URL.

Connect your tools by adding the network to MetaMask and configuring your project with the RPC URL and your wallet's private key (stored securely in an environment variable).

Detailed Instructions

Reading is a call, which is free and doesn't require gas, as it doesn't change the blockchain state. You need the contract's address and ABI. Use a block explorer to find a verified contract, like the Wrapped ETH (WETH) contract on Sepolia: 0x7b79995e5f793A07Bc00c21412e50Ecae098E7f9.

• Process for a Read Call:
  1. Use Etherscan to find the totalSupply function in the "Contract" tab.
  2. In your code, instantiate a contract object using a library like ethers.js.
  3. Call the read-only function.

javascriptCopy
const { ethers } = require('ethers');
const provider = new ethers.JsonRpcProvider('YOUR_RPC_URL');
const contractAddress = '0x7b79995e5f793A07Bc00c21412e50Ecae098E7f9';
const abi = ["function totalSupply() view returns (uint256)"];
const contract = new ethers.Contract(contractAddress, abi, provider);

async function getTotalSupply() {
    const supply = await contract.totalSupply();
    console.log('Total WETH Supply:', ethers.formatEther(supply));
}
getTotalSupply();

Tip: View functions are marked as view or pure in the ABI.

Detailed Instructions

Writing is a transaction that modifies the blockchain. It requires a signed transaction from your wallet, consumes gas, and takes time to be mined. A common first write transaction is approving a token spend. Using the same WETH contract, you might call the approve function.

• Process for a Write Transaction:
  1. Connect your wallet (signer) to the contract instance.
  2. Specify the function, arguments, and optionally adjust gas limits.
  3. Sign and broadcast the transaction, then wait for confirmation.

javascriptCopy
const { ethers } = require('ethers');
const provider = new ethers.JsonRpcProvider('YOUR_RPC_URL');
const wallet = new ethers.Wallet('YOUR_PRIVATE_KEY', provider); // Insecure for production! Use env vars.
const contractAddress = '0x7b79995e5f793A07Bc00c21412e50Ecae098E7f9';
const abi = ["function approve(address spender, uint256 amount) returns (bool)"];
const contract = new ethers.Contract(contractAddress, abi, wallet);

async function approveSpending() {
    const spender = '0xAnotherContractAddress';
    const amount = ethers.parseEther('1.0'); // Approve 1 WETH
    const tx = await contract.approve(spender, amount);
    console.log('Transaction Hash:', tx.hash);
    const receipt = await tx.wait(); // Waits for mining
    console.log('Transaction confirmed in block:', receipt.blockNumber);
}
approveSpending();

Tip: Always check estimated gas and review the transaction on a block explorer after it's mined.