Frequently asked questions

What is Ethereum?

A public blockchain for running smart contracts: programs that execute and enforce themselves, used most visibly for digital assets and financial protocols.

What is ETH used for?

Paying transaction fees, staking to secure the network (validators lock 32 ETH), and acting as collateral and settlement money across the ecosystem's applications.

What was the Merge?

The September 2022 switch from proof-of-work mining to proof-of-stake validation. It removed mining, cut energy use by an estimated 99.9% or more, and set up today's staking economics.

What are layer-2 solutions?

Separate networks that bundle transactions and anchor them to Ethereum for security. They charge much lower fees while keeping a strong link back to the main chain.

How can someone stake ETH?

Run a validator with 32 ETH, join a staking pool, or hold a liquid-staking token; each option carries different requirements and risks. The official staking guide is the right starting point. This site does not provide financial advice.

What is DeFi?

Short for decentralized finance: lending, trading and issuance built from open smart contracts that anyone can use or build on, without an intermediary.

What is gas?

The unit that measures the computational work in a transaction. Fees are paid in ETH per unit of gas; since 2021 each transaction burns its base fee and optionally tips a priority fee to the block proposer.

What is a wallet?

Software or hardware that holds the private keys controlling an account. The wallet never contains the ETH itself; the chain records who owns what, and keys prove ownership. The official wallets guide compares the types.

Can a transaction be reversed?

No. Once a block is finalized, reversing it would require destroying at least one third of all staked ETH. Before finality, rare short reorganizations can shift pending transactions, which is why high-value transfers often wait for finality.

What is a hard fork?

A protocol upgrade that is not backward compatible, adopted by coordination rather than a central authority. Contentious forks can split the chain; that is how Ethereum Classic came to exist in 2016. Routine ones, like every named upgrade since, happen without a split.

What is an ERC-20 token?

An asset that implements the ERC-20 interface standard, making it interchangeable with wallets and exchanges without custom integration. Most tokens in the ecosystem, including major stablecoins, follow it.

What are blobs?

A dedicated data lane added in March 2024 for layer-2 networks to post their transaction data cheaply. Blobs decoupled rollup costs from regular gas prices and cut user fees on rollups by roughly an order of magnitude.

Who runs Ethereum?

No single party. Thousands of independent validators propose and attest blocks, several independent client teams maintain the software, and upgrades ship only when the ecosystem adopts them. The Ethereum Foundation funds research and coordinates, but cannot force a change.

Is ETH a security?

Different regulators in different jurisdictions have taken different views over the years, and the question is not globally settled. This guide takes no position and offers no legal advice.

How do people avoid getting scammed?

Slow down. Verify domains character by character, never share a seed phrase (no legitimate service asks for it), prefer hardware wallets for significant holdings, revoke token approvals you no longer use, and be skeptical of unsolicited help, airdrops and "verify your wallet" pop-ups of any kind.

Glossary

Forty terms that cover most conversations about the network.

Address

The 20-byte identifier of an account, shown in hexadecimal, usually checksummed in mixed case.

Base fee

The algorithmically adjusted portion of a transaction fee, burned on inclusion (EIP-1559).

Beacon chain

The proof-of-stake coordination chain, live since December 2020 and Ethereum's consensus layer since the Merge.

Blob

A short-lived data commitment used by rollups, cheaper than calldata (introduced 2024).

Block

A batch of transactions with a pointer to its parent, produced by one validator per slot.

Block explorer

A website for browsing blocks, transactions, addresses and contracts; Etherscan is the best known.

Burn

Permanent destruction of ETH, chiefly base fees and slashing proceeds.

Client

A software implementation of the protocol, one execution program and one consensus program per node.

Consensus

The process by which the network agrees on one canonical chain.

Contract account

An account whose behavior is defined by deployed code rather than a private key.

dApp

Decentralized application: a user interface over one or more smart contracts.

Epoch

32 slots, about 6.4 minutes; the checkpoint cadence for finality.

EIP

Ethereum Improvement Proposal: the design document stream through which all protocol changes flow.

EOA

Externally owned account, controlled by a private key, usually through a wallet.

ERC

An EIP that defines an application-level standard, such as ERC-20 for tokens.

EVM

The Ethereum Virtual Machine, the execution environment every node replays transactions in.

Finality

The guarantee that a block cannot be reordered except by destroying a large fraction of staked ETH.

Gas

The unit measuring a transaction's computational and storage work; fees are priced per gas unit.

Hard fork

A non-backward-compatible protocol change; routine when coordinated, chain-splitting when contested.

Hardware wallet

A dedicated device that keeps private keys offline and signs transactions in isolation.

Layer 1 (L1)

The Ethereum base chain itself: settlement and data availability for everything above it.

Layer 2 (L2)

A network that executes transactions separately and posts data or proofs back to L1, chiefly rollups.

Mainnet

The primary public network where value is real; contrasted with testnets.

Mempool

The gossip layer of pending transactions awaiting inclusion.

Nonce

A per-account transaction counter enforcing order and preventing replays.

Priority fee

An optional tip that makes a transaction more attractive to block proposers.

Proof of stake

Consensus where weight comes from locked ETH rather than computing power.

Rollup

An L2 that executes off-chain and posts transaction data (optimistic) or validity proofs (zk) to L1.

RPC

The remote procedure interface applications use to talk to nodes.

Sharding

Historic plan for splitting the chain into parallel pieces; largely superseded by rollup-centric scaling plus blob scaling.

Slashing

Forced exit plus burned stake as punishment for provable protocol attacks.

Slot

A 12-second block opportunity; occasionally empty when a proposer misses.

Smart contract

A program deployed at an address, executed by every node and immutable unless designed to change.

Stablecoin

A token designed to hold a stable value, usually against a fiat currency.

Staking

Locking ETH as validator collateral in exchange for rewards and network security duties.

Testnet

A parallel network for safe experimentation; Sepolia and Holesky are the current public ones.

Transaction

A signed instruction moving ETH, calling a contract or deploying code.

TVL

Total value locked: the value deposited in a protocol or ecosystem, a rough size measure.

Validator

A staking participant that proposes and attests blocks.

Wallet

Key management software or hardware; the account's interface to the network.

Zero-knowledge proof

A cryptographic proof that a computation was done correctly without revealing its inputs; the engine of validity rollups.