Solidity Study Notes

Access Control Patterns

Techniques for restricting who can call privileged contract functions, from simple Ownable to role-based access control, safe ownership transfer, and timelocks.

Arrays and Mappings

Arrays are ordered, iterable collections; mappings are hash-based key-value stores with O(1) lookup. Knowing their capabilities, limits, and gas costs is essen…

Auditing Smart Contracts

What a smart contract audit is and is not: the common vulnerability classes auditors hunt, the static, symbolic, and fuzzing tools that assist them, and why ma…

Building a Simple Token Contract

A hands-on walkthrough of writing an ERC-20 token in Solidity, from the standard's required interface to a minimal from-scratch implementation and the safer Op…

Conditionals and Loops in Solidity

Learn how Solidity handles branching with if/else and repetition with for, while, and do-while loops, and why unbounded loops are dangerous in a gas-metered en…

Deploying to Testnets and Mainnet

A practical guide to deploying Solidity contracts with Hardhat: configuring networks and keys, understanding gas and nonces, waiting for confirmations, and ver…

ERC-20 Token Standard

The interface and mechanics behind fungible tokens on Ethereum, covering core functions, the approve/allowance pattern, events, and safe implementation.

ERC-721 NFT Standard

The standard for non-fungible tokens on Ethereum, covering unique token IDs, ownership and metadata, safe transfers with receiver hooks, and minting.

Error Handling with require, revert, assert

Solidity handles errors by reverting state changes. Learn when to use require for input validation, revert with custom errors for gas-efficient failures, and a…

Events and Logging

Events emit indexed logs to the blockchain that off-chain applications can efficiently query, providing a cheap way to record activity that smart contracts the…

Function Modifiers in Solidity

Function modifiers are reusable pieces of code that wrap function bodies to enforce preconditions like access control, using the special _ placeholder to mark…

Functions and Visibility Modifiers

Understand how Solidity functions are declared and the four visibility levels — public, external, internal, and private — plus state mutability keywords like v…

Gas Optimization in Solidity

How the EVM prices computation and storage, and the practical patterns, storage packing, caching, calldata, unchecked math, that reduce transaction costs witho…

Inheritance in Solidity

Inheritance lets contracts reuse and extend each other with the is keyword, virtual/override, super, C3-linearized multiple inheritance, and ordered constructo…

Interfaces and Abstract Contracts

Interfaces declare pure behavior for interoperability, while abstract contracts provide partial, shareable implementation — together they let you program to a…

Oracles and Chainlink Basics

Understand why blockchains need oracles, how Chainlink's decentralized network delivers tamper-resistant data, how to read a price feed with AggregatorV3Interf…

Reentrancy and Common Vulnerabilities

How reentrancy attacks drain contracts by re-entering functions before state updates, plus the defensive patterns and other common Solidity vulnerability class…

Setting Up Remix and Hardhat

Learn the two most common Solidity development environments: the browser-based Remix IDE for quick experiments and the Node.js-based Hardhat framework for prof…

Solidity Best Practices

A practical checklist of security, gas, and maintainability practices for production Solidity: checks-effects-interactions, access control, safe external calls…

Solidity Data Types and Value Types

Explore Solidity's value types and reference types, including sized integers, booleans, addresses, bytes, enums, arrays, structs, and mappings, and how they ar…

Solidity Interview Questions

The concepts interviewers probe most for Solidity roles—data location, visibility, storage layout, gas, security patterns, and the EVM—framed as talking points…

Solidity Quick Reference

A fast-scan cheat sheet of Solidity essentials: types, visibility, data locations, modifiers, error handling, global variables, and common patterns for quick r…

Solidity Syntax and Variables

Understand Solidity's file structure, the difference between state, local, and global variables, and how visibility and data location affect where values live…

Solidity vs Rust for Smart Contracts

Compares Solidity (the dominant EVM language) with Rust (used on Solana, NEAR, and via ink! on Polkadot) across performance, safety, tooling, and ecosystem so…