Ethereum is more than a cryptocurrency. Smart contracts run on the EVM (Ethereum Virtual Machine), a decentralized computer, enabling entirely new forms of applications — DeFi, NFTs, DAOs, and more.

What is the EVM?

The EVM is a sandboxed virtual machine that runs identically on every Ethereum node. Smart contract code is compiled to EVM bytecode and stored on-chain.

Deterministic Execution: Same input → always same output (enables global consensus)
Sandboxed Environment: No external system access; pure on-chain computation only
Oracle Problem: External data (prices, weather) must be supplied via oracles like Chainlink

The Gas System

Every EVM operation has a Gas cost. This is the core mechanism for spam prevention and network resource allocation.

Gas Fee = Gas Used × Gas Price (Gwei)
Post EIP-1559: Base Fee (burned) + Priority Fee (validator tip)

Simple ETH transfer: 21,000 gas
ERC-20 token transfer: ~65,000 gas
Uniswap swap: ~100,000–150,000 gas

How Smart Contracts Work

Smart contracts are immutable code deployed on the blockchain. They execute automatically when conditions are met, and no central authority can stop them.

// Solidity example: Simple Escrow contract
contract Escrow {
    address public buyer;
    address public seller;
    uint public amount;

    constructor(address _seller) payable {
        buyer = msg.sender;
        seller = _seller;
        amount = msg.value;
    }

    function release() external {
        require(msg.sender == buyer, "Not buyer");
        payable(seller).transfer(amount);
    }
}

Interactive EVM Explorer

Use the explorer below to walk through EVM execution flow, analyze gas costs, examine contract structure, and explore DApp architecture.

DApp Architecture

Decentralized applications (DApps) consist of a blockchain layer (smart contracts) and a frontend (Web3.js/ethers.js).

MetaMask: Acts as user wallet, signs transactions
Infura/Alchemy: RPC node infrastructure
ethers.js: Contract interaction library
The Graph: On-chain data indexing

Smart Contract Security

Contract vulnerabilities can cause hundreds of millions in losses. Key security patterns:

Reentrancy: Defend with Checks-Effects-Interactions pattern
Integer Overflow: Built-in checks in Solidity 0.8+
Access Control: Use OpenZeppelin AccessControl/Ownable

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Ethereum (EVM) Smart Contract Complete Guide: From Execution to DApp Development