⛓️ Blockchain Learning Repository

---

📅 2026-01-02

• Learned: Solidity Basics (Contract structure, State variables, Constructors) & Smart Contract Deployment with Ethers.js
• Location: blockchain-day1/contracts/HelloWorld.sol && blockchain-day1/scripts/deploy.js

---

📅 2026-01-03

• Learned: Reading vs Writing Blockchain State (Call vs Transaction), Gas Concept, Transaction Lifecycle, Role of Signer in State-Changing Operations
• Location: blockchain-day1/contracts/HelloWorld.sol && blockchain-day1/scripts/interact.js

---

📅 2026-01-04

• Learned: Signer vs msg.sender (Off-chain vs On-chain Identity), Why Smart Contracts Cannot Call External APIs, Event-based Communication & Oracle Architecture (Conceptual)
• Location: blockchain-day1/contracts/HelloWorld.sol

---

📅 2026-01-05

• Learned: Practical Oracle Implementation, Event Emission & Listening, Off-chain Listener using Node.js, Sending External Data Back to Blockchain via Transactions, End-to-End Oracle Workflow
• Location: blockchain-day1/contracts/OracleDemo.sol && blockchain-day1/scripts/oracleListener.js && blockchain-day1/scripts/interact.js

📅 2026-01-06

• Learned: Complex Data Structures (Mappings & Structs) for efficient data retrieval.
• Location: blockchain-day1/contracts/UserRegistry.sol

📅 2026-01-07

• Learned: Access Control patterns and the use of Function Modifiers for security.
• Location: blockchain-day1/contracts/SecureContract.sol

📅 2026-01-08

• Learned: ERC-20 Token standards, managing total supply, and transfer logic.
• Location: blockchain-day1/contracts/SimpleToken.sol

📅 2026-01-09

• Learned: Robust Error Handling using Require, Revert, and Assert to manage gas.
• Location: blockchain-day1/contracts/ErrorHandling.sol

📅 2026-01-10

• Learned: Payable functions, the receive fallback, and sending Ether from contracts.
• Location: blockchain-day1/contracts/EtherWallet.sol