What is Ethereum? A beginner's guide to the world computer

Ethereum is a public blockchain that can run programs, not just record payments. Its native asset, ether (ETH), pays for that computing and secures the network through staking. This lesson explains how it works, what people actually build on it, and the risks worth understanding before you use it.

The big idea: a shared computer nobody owns

Bitcoin, which you met earlier in this course, is mainly a ledger for one currency. Ethereum asked a broader question: what if a blockchain could also store and run software that anyone can use?

A helpful picture is a giant public vending machine. Anyone can stock it with a new kind of product, anyone can use it, and it follows the same rules for every customer. No shopkeeper can refuse to serve you or quietly change the prices behind the counter.

Ethereum went live in July 2015, launched by programmer Vitalik Buterin and a group of co-founders. Thousands of independent computers, called nodes, each keep a copy of its data and check every change against the same rules.

Smart contracts, in plain English

The programs that run on Ethereum are called smart contracts. Despite the name, they are not legal documents. They are pieces of code that hold funds and follow instructions automatically when certain conditions are met.

For example, a contract could say: “If someone deposits token A, give them the right amount of token B at the current pool rate.” Once deployed, it runs exactly as written, around the clock, for anyone with an internet connection.

That predictability is the strength and the weakness. Code does not get tired or play favorites, but it also does not forgive bugs. A flaw in a contract can be exploited, and blockchain transactions usually cannot be reversed.

ETH and gas: paying for computing

Every action on Ethereum, from sending ETH to swapping tokens, uses some computing work. That work is measured in units called gas, and the fee is paid in ETH. Think of gas like the meter in a taxi: a simple trip costs less than a complicated one.

Fees exist for a reason. They stop people from flooding the network with junk and pay the participants who process transactions. Your fee has two parts: a base fee set automatically by the network, and an optional tip to encourage faster inclusion. Since 2021 the base fee is burned (permanently removed), not paid to anyone.

Proof of stake since The Merge

Every blockchain needs a way for strangers to agree on which transactions are valid. Ethereum originally used mining, like Bitcoin. On September 15, 2022, an upgrade called The Merge switched it to proof of stake. According to ethereum.org, this cut the network's energy use by roughly 99.95%.

Under proof of stake, participants called validators lock up ETH as a security deposit. They propose and check new blocks and earn rewards for doing it honestly. If a validator is offline, it misses rewards and loses small amounts. If it provably cheats, such as signing two conflicting blocks, part of its deposit is destroyed, a penalty called slashing.

How staking works for regular people

Staking means committing ETH to help secure the network in exchange for rewards. Running your own validator requires at least 32 ETH and a computer that stays online. Since the Pectra upgrade, a single validator can hold up to 2,048 ETH.

Most people who stake use an easier route, each with its own trade-offs:

• Home staking: you run the hardware and keep the keys. Most control, most responsibility.
• Pooled or liquid staking: you deposit any amount into a protocol that stakes on your behalf. This adds smart contract risk and reliance on the operators.
• Exchange staking: a company stakes for you. Simplest, but the company holds your ETH and sets the terms.

Our staking guide covers these choices in more depth.

Layer 2s: Ethereum's express lanes

Ethereum's main network can only process so much at once, and busy periods once pushed fees very high. The approach the community chose is to keep the main chain secure and push most everyday activity onto layer 2 networks.

Picture a busy highway with express lanes built on top. Layer 2s, often called rollups, bundle many transactions together, process them cheaply, then post a compact record back to Ethereum. Several recent upgrades exist specifically to make that posting cheaper. See layer 2s explained for how they work and the extra risks they carry.

What people actually use Ethereum for

• Stablecoins: stablecoins are tokens designed to track a currency such as the US dollar. Large amounts are issued on Ethereum and its layer 2s, and they are used for payments, trading and savings. Learn more on our stablecoins page.
• Decentralized finance: DeFi apps let people swap, lend and borrow through smart contracts instead of a bank. Start with what is DeFi.
• NFTs: non-fungible tokens are unique tokens used for digital art, collectibles, tickets and in-game items.
• Tokenization: tokenization represents real-world assets, such as government bonds or fund shares, as tokens on a blockchain. Some traditional financial firms now issue products this way.
• Identity and logins: an Ethereum address can serve as a single sign-in across many apps.

Notable upgrades from 2022 to 2026

Ethereum changes through scheduled network upgrades. Here are the ones beginners are most likely to hear about, with dates from the official ethereum.org roadmap:

Risks to understand

• Price swings: ETH's value can rise or fall sharply. Only use money you can afford to see drop.
• Smart contract bugs: apps can be hacked even when Ethereum itself works fine.
• Scams and malicious approvals: fake apps trick people into signing transactions that drain their wallets. Read about phishing and wallet drainers.
• Layer 2 and bridge risk: many layer 2s still rely on operators or upgrade keys, and bridges between networks have been frequent hacking targets.
• Staking risk: slashing, operator failures and smart contract risk in staking protocols.
• Complexity and concentration: a few large staking providers and software clients carry a lot of weight, and upgrades sometimes run late.
• Regulation: US rules for tokens, staking and DeFi are still evolving.

Where to go next

To use Ethereum at all, you need a wallet, and understanding what a wallet really does is the single most useful safety step you can take. Continue the course with lesson 5, crypto wallets explained, then lesson 6, the seed phrase guide.

Updated October 4, 2026 by The Crypto Guide editorial team. Educational content, not financial, legal or tax advice. Spot an error? Request a correction.