What Is an ERC20 Token? Definition and Technical Standard Explained

Foundry is a comprehensive Ethereum development toolchain with Forge for building, testing, and deploying smart contracts; Anvil as a local blockchain node; Cast for interacting with contracts; and Chisel for Solidity testing. The ERC20 standard defines fungible token interfaces with required functions (name, symbol, decimals, totalSupply, balanceOf, transfer, transferFrom, approve) and events (Transfer, Approval). OpenZeppelin provides pre-verified, secure implementations. Creating a mintable and burnable token involves extending ERC20 with ERC20Burnable for minting and burning capabilities, using Ownable for access control. Solidity handles decimals by multiplying amounts by 10^18 since it doesn't support decimal numbers directly. Foundry testing uses setup functions, test accounts with makeAddress, assert functions, prank for executing transactions as specific accounts, expectRevert for error conditions, and expectEmit for event verification. Tests cover minting, burning, allowances, transfers, and unauthorized access attempts.

OpenZeppelin is an industry-standard library for smart contracts. The Contracts Wizard (wizard.openzeppelin.com) generates code for ERC20 tokens with configurable options: name, symbol, initial supply, mintability, and pause functionality. Minting creates new tokens, with only the owner able to call mint(). Remix is an online IDE with file explorer, compiler, and deployment tools. Compilation produces a green checkmark when successful. To deploy an ERC20 token: ensure compilation is successful, select 'Injected Provider - MetaMask', connect MetaMask, enter recipient and owner addresses, and click Deploy. The transaction costs gas (measured in RON on Ronin). After deployment, the contract address is displayed. The deployed contract includes all ERC20 functions from the import, such as approve(), transferFrom(), balanceOf(), and transfer(). Token decimals (default 18) determine how fractional values are represented, as blockchains only store whole numbers.

This tutorial demonstrates how to create, deploy, and verify an ERC20 token on the Ethereum blockchain using Solidity programming language and OpenZeppelin's secure, audited contracts, covering the entire process from development environment setup to deployment on testnet and mainnet.

The tutorial implements the ERC20 token standard using OpenZeppelin's battle-tested contracts. The createMemeToken function accepts parameters for token name, symbol, description, and image URL. The function is public and returns the newly created token address. The ERC20 constructor is called with name and symbol parameters, and the initial supply is minted to the sender. The max supply is set to 1 million tokens with 18 decimals for standard divisibility. The initial supply is calculated as 20% of the max supply multiplied by the decimal value.

This tutorial demonstrates how to create an ERC-20 compliant token using Solidity and OpenZeppelin's pre-built contracts, following test-driven development principles with Truffle framework. The process involves setting up a Truffle project, writing failing tests first, implementing the token contract by inheriting from OpenZeppelin's ERC20 contract, configuring the compiler version, and deploying to the Rinkeby testnet. Key concepts include handling 18 decimal places for token supply, using web3 utilities for number conversion, and understanding the migration system for deployment.

ERC-20 tokens are digital currencies built on the Ethereum blockchain that enable decentralized financial transactions without traditional banking intermediaries, allowing users to create, distribute, and trade tokens through transparent, publicly verifiable systems like Etherscan.

DeFi (Decentralized Finance) is a financial ecosystem built on blockchain technology that provides open-source, transparent services without central authority. Transactions use smart contracts that establish consensus through pre-established code protocols, ensuring faster execution and reduced human error but potentially containing vulnerabilities. Automated Market Makers (AMMs) are decentralized exchanges using algorithms to determine asset prices through smart contracts, operating with asset pairs rather than traditional order books. AMMs establish single prices visible to all participants and rely on liquidity pools funded by third parties who receive transaction fee percentages. Popular AMMs include Uniswap (most popular, open-source, supports ERC-20 tokens), Balancer (supports up to 8 tokens per pool), Kyber Network (DAO-governed), and Curve (low fees for similar tokens).

DeFi trading uses Automated Market Makers (AMMs) instead of traditional order books. An AMM is a smart contract holding assets on both sides of a trading pair, continuously quoting prices. Users send tokens to the smart contract to receive desired assets from the pool. Oracles provide external price data to smart contracts. Liquidity providers stake equal amounts of both assets in trading pairs, earning fees from traders. This has become yield farming, where people profit by holding digital assets. Uniswap is the most popular DeFi exchange, with fees accumulating to liquidity providers who can earn around 30% annual percentage yield.

DeFi (Decentralized Finance) represents financial services built on blockchain technology, primarily Ethereum. The ERC20 token standard enables creation of digital assets representing various utilities. DeFi operates on three pillars: lending/borrowing platforms using smart contracts, decentralized exchanges with automated market makers, and derivatives including insurance, synthetic assets, and predictive markets. Liquidity providers supply funds to protocols, earning fees from trades. Yield farming allows participants to earn additional rewards by staking LP tokens, creating economic incentives for ecosystem participation.

Liquidity pools are smart contract vaults holding two tokens (e.g., Ethereum + USDT) that enable instant trading. Liquidity providers deposit equal value of both tokens and receive LP tokens representing their share. Providers earn fees (e.g., 0.3%) from every swap, with more volume meaning more earnings. Impermanent loss occurs when token prices diverge - the pool rebalances tokens, causing providers to hold less of the appreciating token and more of the depreciating one. Yield farming is earning rewards by locking/staking crypto in DeFi protocols. Types include liquidity pool farming (deposit two tokens, earn fees + reward tokens), staking (single asset, lower risk), borrowing/lending farming, and auto-compounding farms. Rewards come from trading fees, native tokens, lending interest, and boosted incentives.

Smart contract security requires rigorous testing (75-80% of development time) due to blockchain immutability, with key vulnerabilities including reentrancy attacks, on-chain randomness manipulation, overflow/underflow bugs, and price oracle exploits. Best practices include using the check-effects-interactions pattern, avoiding tx.origin in favor of msg.sender, implementing proper gas optimizations without sacrificing security, and utilizing formal verification tools alongside manual code reviews. Auditing combines static analysis, symbolic execution, fuzz testing, and human review to identify vulnerabilities before deployment.

The most effective smart contract security practice is writing comprehensive tests that cover various scenarios, including edge cases and attack vectors. Testing should cover scenarios like maximum value transfers, minimum value transfers, and zero-value transfers. Comprehensive testing can cover approximately 50% of vulnerabilities found in audits. Common vulnerability patterns vary by chain and protocol type: Solana-specific issues include account handling problems, reentrancy vulnerabilities are common across chains, and lending protocols frequently have issues with flash loans.

This video presents 22 essential security checkpoints for identifying vulnerabilities in smart contracts during initial reviews, including front-running/back-running attacks, handling of small amounts and zero inputs, gas griefing with external calls, weird ERC-20 token behaviors, price manipulation, blacklisted token exploits, overflow/underflow issues, block reorg attacks, reentrancy, sybil attacks on incentives, flash loans, accepting data from any address, internal accounting inflation, precision loss in validations, address lifecycle vulnerabilities, unexpected receiver addresses, selector clashing in upgradability patterns, signature-related exploits, and hash collision issues.

Smart contracts face multiple categories of vulnerabilities: (1) Arithmetic errors including integer overflow/underflow where values wrap around at limits, and decimal handling issues with ERC20 tokens; (2) Re-entrancy attacks where recursive calls drain funds before balances decrement; (3) Uninitialized contracts where missing initialization leaves variables in default states; (4) Access control failures when sensitive functions are publicly accessible; (5) Oracle manipulation allowing false off-chain data injection; (6) On-chain randomness exploits where any user can manipulate sources; (7) Denial of Service attacks freezing or destroying contracts; (8) Complex logic errors distinguishing bugs from exploits; (9) Delegate call vulnerabilities enabling contract tunneling; (10) Compiler version issues causing unexpected behavior. Solidity 0.8.0+ automatically checks overflow/underflow, replacing SafeMath. Prevention requires proper access control modifiers, re-entrancy guards, and avoiding TX.origin for security checks.

This video presents the 10 most common vulnerabilities found in smart contract audit contests, which are critical security events where developers compete to find bugs in protocols before mainnet deployment. The vulnerabilities include: (1) Depositor inflation attack in ERC-4626 vaults where the first depositor exploits rounding issues to steal funds; (2) Using transfer instead of safeTransferFrom which doesn't verify transfer success and enables re-entrancy attacks; (3) Missing validation and admin checks that allow unauthorized function calls; (4) Missing checks for active L2 sequencers that can go offline; (5) Classic re-entrancy vulnerability allowing functions to be called repeatedly; (6) Rounding precision loss issues from Solidity's lack of floating-point arithmetic; (7) Using spot price instead of TWAP enabling price manipulation attacks; (8) Incorrect implementation of upgradeability with hardcoded values; (9) No slippage check in custom vaults and pools allowing users to sign trades at different prices. These vulnerabilities are commonly overlooked by developers and auditors despite being critical security risks.

Governance tokens are cryptoassets whose holders have authority to make decisions for Decentralized Autonomous Organizations (DAOs) or modify programming code. A DAO is an organization structured, governed, and administered through smart contracts and computer codes, resulting in decentralized operation. Unlike traditional corporate structures, DAOs operate through automated smart contracts fed by external data via oracles, with decisions made through votes represented by governance tokens. Uniswap operates as a DAO with UNI as its governance token.

A DAO (Decentralized Autonomous Organization) functions as an 'electronic boardroom' where organizations make collective decisions and allocate resources. Unlike traditional boardrooms where voting is confidential, DAO governance is completely transparent—every wallet's vote is publicly visible on the blockchain. A wallet address is an EOA (Externally Owned Account) with a private key that can launch smart contracts. Smart contracts have the same address format as EOAs, creating confusion in block explorers. DAO voting typically operates on a one-token-one-vote basis, where each token represents one vote. When setting up a DAO, the voting module requires configuring two critical parameters: the voting time period (recommended 15 minutes for classroom exercises) and the minimum approval threshold (recommended 50%). ERC20 tokens are the standard format for most tokens on Ethereum and Polygon, with approximately 90% of major tokens following this standard. The ability for anyone to create tokens creates both opportunities and risks, as scammers can create fraudulent tokens. Legitimate tokens typically have significant market capitalization and trading volume.

Decentralized Autonomous Organizations (DAOs) use token-based voting for governance. Token holders vote on proposals with power proportional to balance. The process: (1) proposals submitted as transactions, (2) token holders vote for/against, (3) votes tallied by balance, (4) successful proposals executed. This enables community governance without centralized control. Oracle networks provide external data (prices, random numbers) to contracts, with decentralized networks like Chainlink aggregating data from multiple sources for security.

DAO (Decentralized Autonomous Organization) is an organization managed through smart contracts on the blockchain, where rules and regulations are converted into computer code. Governance tokens create voting rights, enabling token holders to participate in decisions about protocol updates, budget allocation, fee structures, and partnerships. The governance mechanism involves proposal creation by token holders or founding teams, followed by community voting. If proposals receive sufficient votes, smart contracts automatically execute them. Key advantages include censorship resistance, global participation, and complete transparency. Uniswap serves as a successful real-world example, demonstrating how governance tokens enable community-driven decision-making for protocol deployment and expansion.

DAOs use governance tokens similar to traditional stock ownership, where each token grants voting rights and can provide returns comparable to dividends. Unlike traditional shareholder meetings limited to once or twice yearly, DAO governance enables continuous participation. Vote delegation allows token holders to delegate power to trusted representatives, with delegation being highly liquid and revocable at any time. DAOs enable meritocratic governance where proposals are evaluated on intrinsic merit rather than proposer identity, wealth, or credentials. Unknown individuals can propose and implement changes, potentially becoming influential based solely on contribution value.