️ Languages & Runtimes

• Solidity: The most popular contract language on Ethereum—JavaScript-like syntax for writing smart contracts.
• Vyper: A Python-inspired Ethereum language focused on simplicity and auditability.
• Rust / Ink!: A systems-language (Rust) variant used for writing contracts on Substrate/Polkadot via the Ink! framework.
• Move: A Rust-influenced language created by Diem (Facebook) for safe resource management in smart contracts.
• EVM (Ethereum Virtual Machine): The runtime environment that executes Ethereum smart-contract bytecode.

Compilation & Deployment

• Compiler (solc, vyper): A tool that converts your high-level code into low-level EVM bytecode.
• Bytecode: The binary instructions the EVM executes—deployed to chain.
• ABI (Application Binary Interface): A JSON spec of your contract’s functions/events—used by front-ends and scripts to interact.
• Gas Limit / Gas Price: Max gas you allow and price per gas unit you’re willing to pay at deployment/execution.
• Constructor: A special function that runs once, during contract deployment, to initialize state.

Auditing & Verification

• Audit: A systematic security review of contract code by experts, looking for vulnerabilities.
• Formal Verification: Mathematically proving your contract behaves exactly as specified.
• Reentrancy: A bug where a contract calls back into itself before state updates—famous for TheDAO hack.
• Integer Overflow/Underflow: When arithmetic exceeds its max/min value—now prevented by SafeMath libraries or built-in checks.
• Access Control: Patterns (Ownable, RBAC) that restrict who can call sensitive functions.

Gas & Optimization

• Gas: The “fuel” paid to execute contract code; each opcode has a gas cost.
• Storage vs. Memory: Persistent (storage) is expensive; temporary (memory/calldata) is cheaper.
• View / Pure Functions: Read-only (view) or side-effect-free (pure) functions that cost no gas when called externally.
• Inlining & Assembly: Embedding optimized EVM bytecode or small functions inlined to reduce gas.
• Constant Folding: Letting the compiler precompute static expressions to save gas at runtime.

🧪 Testing & Tooling

• Unit Test: Small, isolated tests for individual functions (e.g., with Hardhat, Truffle or Foundry).
• Integration Test: End-to-end tests that deploy contracts and simulate user interactions.
• Fuzzing: Automated testing with random inputs to uncover edge-case bugs.
• Hardhat / Truffle / Foundry: Development frameworks offering local chains, testing suites, and deployment scripts.
• Ethers.js / Web3.js: JavaScript libraries for interacting with deployed contracts in your front-end or scripts.

Pin this thread for quick reference in the lab. Spot any terms missing or need code examples? Drop your suggestions below!