> ## Documentation Index > Fetch the complete documentation index at: https://base-a060aa97-eb-mini-app-ia-overhaul.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Learn to Build Smart Contracts and Onchain Apps > Base Learn is a comprehensive, free guide to learning smart contract and onchain app development. ![Welcome](https://mintlify.s3.us-west-1.amazonaws.com/base-a060aa97-eb-mini-app-ia-overhaul/images/learn/welcome/Base_Learn_Hero.png) ## Introduction Welcome to Base Learn, your guide to learning smart contract development. Base Learn's curriculum has been expertly crafted to equip you with the skills and knowledge needed to build and deploy smart contracts on Base, or any EVM-compatible chain, including Ethereum, Optimism, and many more. Plus, you'll be eligible to earn NFTs as you complete each module, showcasing your mastery of the material. Whether you're a curious novice or a seasoned pro looking to stay ahead of the game, our dynamic lessons cater to all levels of experience. You can start with the basics and work your way up, or dive straight into the more advanced concepts and push your limits to new heights. Begin your journey today! ## What you can learn in this program Base Learn covers the following topics. If you're looking for quickstarts, or deeper guides on advanced topics, check out our [Base Builder Tutorials](/)! ### [Ethereum Applications](/learn/introduction-to-ethereum/ethereum-applications) * Describe the origin and goals of the Ethereum blockchain * List common types of applications that can be developed with the Ethereum blockchain * Compare and contrast Web2 vs. Web3 development * Compare and contrast the concept of "ownership" in Web2 vs. Web3 ### [Gas Use in Ethereum Transactions](/learn/introduction-to-ethereum/gas-use-in-eth-transactions) * Explain what gas is in Ethereum * Explain why gas is necessary in Ethereum * Understand how gas works in Ethereum transactions ### [EVM Diagram](/learn/introduction-to-ethereum/evm-diagram) * Diagram the EVM ### [Setup and Overview](/learn/hardhat/hardhat-setup-overview/hardhat-setup-overview-sbs) * Install and create a new Hardhat project with Typescript support * Describe the organization and folder structure of a Hardhat project * List the use and properties of hardhat.config.ts ### [Testing with Hardhat and Typechain](/learn/hardhat/hardhat-testing/hardhat-testing-sbs) * Set up TypeChain to enable testing * Write unit tests for smart contracts using Mocha, Chai, and the Hardhat Toolkit * Set up multiple signers and call smart contract functions with different signers ### [Etherscan](/learn/hardhat/etherscan/etherscan-sbs) * List some of the features of Etherscan * Read data from the Bored Ape Yacht Club contract on Etherscan * Write data to a contract using Etherscan. ### [Deploying Smart Contracts](/learn/hardhat/hardhat-deploy/hardhat-deploy-sbs) * Deploy a smart contract to the Base Sepolia Testnet with hardhat-deploy * Deploy a smart contract to the Sepolia Testnet with hardhat-deploy * Use BaseScan to view a deployed smart contract ### [Verifying Smart Contracts](/learn/hardhat/hardhat-verify/hardhat-verify-sbs) * Verify a deployed smart contract on Etherscan * Connect a wallet to a contract in Etherscan * Use etherscan to interact with your own deployed contract ### [Hardhat Forking](/learn/hardhat/hardhat-forking/hardhat-forking) * Use Hardhat Network to create a local fork of mainnet and deploy a contract to it * Utilize Hardhat forking features to configure the fork for several use cases ### ['Introduction to Remix'](/learn/introduction-to-solidity/introduction-to-remix) * List the features, pros, and cons of using Remix as an IDE * Deploy and test the Storage.sol demo contract in Remix ### [Deployment in Remix](/learn/introduction-to-solidity/deployment-in-remix) * Deploy and test the Storage.sol demo contract in Remix ### [Hello World](/learn/contracts-and-basic-functions/hello-world-step-by-step) * Construct a simple "Hello World" contract * List the major differences between data types in Solidity as compared to other languages * Select the appropriate visibility for a function ### [Basic Types](/learn/contracts-and-basic-functions/basic-types) * Categorize basic data types * List the major differences between data types in Solidity as compared to other languages * Compare and contrast signed and unsigned integers ### [Test Networks](/learn/deployment-to-testnet/test-networks) * Describe the uses and properties of the Base testnet * Compare and contrast Ropsten, Rinkeby, Goerli, and Sepolia ### [Deployment to Base Sepolia](/learn/deployment-to-testnet/deployment-to-base-sepolia-sbs) * Deploy a contract to the Base Sepolia testnet and interact with it in \[BaseScan] ### [Contract Verification](/learn/deployment-to-testnet/contract-verification-sbs) * Verify a contract on the Base Sepolia testnet and interact with it in \[BaseScan] ### [Control Structures](/learn/control-structures/control-structures) * Control code flow with `if`, `else`, `while`, and `for` * List the unique constraints for control flow in Solidity * Utilize `require` to write a function that can only be used when a variable is set to `true` * Write a `revert` statement to abort execution of a function in a specific state * Utilize `error` to control flow more efficiently than with `require` ### [Storing Data](/learn/storage/simple-storage-sbs) * Use the constructor to initialize a variable * Access the data in a public variable with the automatically generated getter * Order variable declarations to use storage efficiently ### [How Storage Works](/learn/storage/how-storage-works) * Diagram how a contract's data is stored on the blockchain (Contract -> Blockchain) * Order variable declarations to use storage efficiently * Diagram how variables in a contract are stored (Variable -> Contract) ### [Arrays](/learn/arrays/arrays-in-solidity) * Describe the difference between storage, memory, and calldata arrays ### [Filtering an Array](/learn/arrays/filtering-an-array-sbs) * Write a function that can return a filtered subset of an array ### [Mappings](/learn/mappings/mappings-sbs) * Construct a Map (dictionary) data type * Recall that assignment of the Map data type is not as flexible as for other data types/in other languages * Restrict function calls with the `msg.sender` global variable * Recall that there is no collision protection in the EVM and why this is (probably) ok ### [Function Visibility and State Mutability](/learn/advanced-functions/function-visibility) * Categorize functions as public, private, internal, or external based on their usage * Describe how pure and view functions are different than functions that modify storage ### [Function Modifiers](/learn/advanced-functions/function-modifiers) * Use modifiers to efficiently add functionality to multiple functions ### [Structs](/learn/structs/structs-sbs) * Construct a `struct` (user-defined type) that contains several different data types * Declare members of the `struct` to maximize storage efficiency * Describe constraints related to the assignment of `struct`s depending on the types they contain ### [Inheritance](/learn/inheritance/inheritance-sbs) * Write a smart contract that inherits from another contract * Describe the impact inheritance has on the byte code size limit ### [Multiple Inheritance](/learn/inheritance/multiple-inheritance) * Write a smart contract that inherits from multiple contracts ### [Abstract Contracts](/learn/inheritance/abstract-contracts-sbs) * Use the virtual, override, and abstract keywords to create and use an abstract contract ### [Imports](/learn/imports/imports-sbs) * Import and use code from another file * Utilize OpenZeppelin contracts within Remix ### [Error Triage](/learn/error-triage/error-triage) * Debug common solidity errors including transaction reverted, out of gas, stack overflow, value overflow/underflow, index out of range, etc. ### [The New Keyword](/learn/new-keyword/new-keyword-sbs) * Write a contract that creates a new contract with the new keyword ### ['Contract to Contract Interaction'](/learn/interfaces/contract-to-contract-interaction) * Use interfaces to allow a smart contract to call functions in another smart contract * Use the `call()` function to interact with another contract without using an interface ### [Events](/learn/events/hardhat-events-sbs) * Write and trigger an event * List common uses of events * Understand events vs. smart contract storage ### [Address and Payable in Solidity](/learn/address-and-payable/address-and-payable) * Differentiate between address and address payable types in Solidity * Determine when to use each type appropriately in contract development * Employ address payable to send Ether and interact with payable functions ### [Minimal Token](/learn/token-development/minimal-tokens/minimal-token-sbs) * Construct a minimal token and deploy to testnet * Identify the properties that make a token a token ### [The ERC-20 Token Standard](/learn/token-development/erc-20-token/erc-20-standard) * Analyze the anatomy of an ERC-20 token * Review the formal specification for ERC-20 ### [ERC-20 Implementation](/learn/token-development/erc-20-token/erc-20-token-sbs) * Describe OpenZeppelin * Import the OpenZeppelin ERC-20 implementation * Describe the difference between the ERC-20 standard and OpenZeppelin's ERC20.sol * Build and deploy an ERC-20 compliant token ### [The ERC-721 Token Standard](/learn/token-development/erc-721-token/erc-721-standard) * Analyze the anatomy of an ERC-721 token * Compare and contrast the technical specifications of ERC-20 and ERC-721 * Review the formal specification for ERC-721 ### [ERC-721 Token](/learn/token-development/erc-721-token/erc-721-sbs) * Analyze the anatomy of an ERC-721 token * Compare and contrast the technical specifications of ERC-20 and ERC-721 * Review the formal specification for ERC-721 * Build and deploy an ERC-721 compliant token * Use an ERC-721 token to control ownership of another data structure ### [Wallet Connectors](/learn/onchain-app-development/frontend-setup/wallet-connectors) * Identify the role of a wallet aggregator in an onchain app * Debate the pros and cons of using a template * Scaffold a new onchain app with RainbowKit * Support users of EOAs and the Coinbase Smart Wallet with the same app ### [Building an Onchain App](/learn/onchain-app-development/frontend-setup/building-an-onchain-app) * Identify the role of a wallet aggregator in an onchain app * Debate the pros and cons of using a template * Add a wallet connection to a standard template app ### [The `useAccount` Hook](/learn/onchain-app-development/reading-and-displaying-data/useAccount) * Implement the `useAccount` hook to show the user's address, connection state, network, and balance * Implement an `isMounted` hook to prevent hydration errors ### [The `useReadContract` Hook](/learn/onchain-app-development/reading-and-displaying-data/useReadContract) * Implement wagmi's `useReadContract` hook to fetch data from a smart contract * Convert data fetched from a smart contract to information displayed to the user * Identify the caveats of reading data from automatically-generated getters ### [Configuring `useReadContract`](/learn/onchain-app-development/reading-and-displaying-data/configuring-useReadContract) * Use `useBlockNumber` and the `queryClient` to automatically fetch updates from the blockchain * Describe the costs of using the above, and methods to reduce those costs * Configure arguments to be passed with a call to a `pure` or `view` smart contract function * Call an instance of `useReadContract` on demand * Utilize `isLoading` and `isFetching` to improve user experience ### [The `useWriteContract` hook](/learn/onchain-app-development/writing-to-contracts/useWriteContract) * Implement wagmi's `useWriteContract` hook to send transactions to a smart contract * Configure the options in `useWriteContract` * Display the execution, success, or failure of a function with button state changes, and data display ### [The `useSimulateContract` hook](/learn/onchain-app-development/writing-to-contracts/useSimulateContract) * Implement wagmi's `useSimulateContract` and `useWriteContract` to send transactions to a smart contract * Configure the options in `useSimulateContract` and `useWriteContract` * Call a smart contract function on-demand using the write function from `useWriteContract`, with arguments and a value