Free lesson 1 of 9 from Web3 & Smart Contract Security — Audit blockchain code for millions on the line. No account, no card.
A public blockchain is a shared, append-only ledger replicated across many independent nodes. Once a transaction is confirmed, it is effectively permanent. This immutability is the core reason smart contract security matters so much: unlike a web server, you usually cannot simply patch a deployed contract, and a single bug can leak funds forever.
Programs that run on the chain are called smart contracts. They hold balances, enforce rules, and execute automatically when someone sends them a transaction. On many chains they are written in Solidity and compiled to bytecode.
The EVM (Ethereum Virtual Machine) is the runtime that executes contract bytecode deterministically on every node. Each operation costs gas, a unit that meters computation and storage. Users pay for gas so the network cannot be spammed with infinite loops.
Never learn by touching real value. Install Foundry and spin up a local chain with anvil, or use a public testnet where coins have no real worth. Deploy your own simple contract, send it transactions, and read its storage. This sandbox is where every technique in this course belongs.
anvil, and deploy a tiny contract that stores a number. Send a transaction to change it and read the value back.⚖️ For authorized, legal testing only.
9 lessons · knowledge checks · final exam · verifiable certificate · in-browser Live-Lab
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