Ethereum, the EVM, Accounts and Gas

A world computer with metered execution

Ethereum is a programmable blockchain. Its state is a set of accounts: externally owned accounts (EOAs), controlled by private keys, and contract accounts, which hold code and storage and run only when called. Every account has an address (20 bytes) and an ether balance, measured in wei (1 ether = 10^18 wei; 1 gwei = 10^9 wei). A transaction is a signed message from an EOA that transfers ether, deploys a contract or calls a contract function; each has a nonce to prevent replay. Contracts run on the Ethereum Virtual Machine (EVM), a deterministic stack machine that every node executes identically. Every operation costs gas, which prevents infinite loops and prices scarce resources: storage writes are expensive, arithmetic is cheap. Since EIP-1559, the fee is gas used × (base fee + priority fee): the base fee adjusts automatically with demand and is burned, and the priority fee (tip) goes to the validator. You set a gas limit; if execution runs out of gas, it reverts but the gas is still spent. Many EVM-compatible chains and layer 2 rollups (Arbitrum, Optimism, Base, zkSync and others) run the same Solidity code with lower fees.

Calculating a transaction fee

Fee arithmetic with EIP-1559, in wei (shown as Solidity-style constants).

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.24;

// Illustrative fee arithmetic (all values in wei)
contract FeeMath {
    uint256 public constant GWEI = 1e9;

    function fee(uint256 gasUsed, uint256 baseFeeGwei, uint256 tipGwei)
        external
        pure
        returns (uint256 totalWei, uint256 burnedWei, uint256 toValidatorWei)
    {
        burnedWei = gasUsed * baseFeeGwei * GWEI;       // base fee is burned
        toValidatorWei = gasUsed * tipGwei * GWEI;      // priority fee goes to the validator
        totalWei = burnedWei + toValidatorWei;
    }
}

// A plain ether transfer uses 21,000 gas.
// With a 20 gwei base fee and a 2 gwei tip:
//   21,000 * 22 gwei = 462,000 gwei = 0.000462 ether

A taxi meter

Gas is a taxi meter for computation: every step of your contract adds to the fare. The base fee is the city's surge price (which is destroyed rather than kept), the tip persuades a driver to pick you up first, and the gas limit is the maximum fare you agreed to pay.

त्वरित जाँच: What happens if a transaction runs out of gas?

• It completes for free
• The validator pays the rest
• It is retried automatically
• Its state changes are reverted, but the gas used is still paid