What is Ethereum?

If Bitcoin proved that digital money without a central authority could work, Ethereum asked a bigger question: what if the same kind of decentralized network could run any program, not just track a currency? Launched in 2015, Ethereum became the foundation for most of what people now think of as the wider crypto world, the tokens, the apps, the financial protocols. It is the second-largest cryptocurrency and arguably the most consequential platform in the space. This guide explains what it is and how it differs from Bitcoin.

How it differs from Bitcoin

The simplest way to understand Ethereum is by contrast. Bitcoin is designed to do one thing extremely well: be sound, scarce digital money. Ethereum is designed to be a general-purpose platform, a world computer, that can run almost any logic you can program. Bitcoin is a calculator built for one calculation. Ethereum is closer to a smartphone that runs apps. Both use a blockchain, but they aim at very different goals.

This is why so much of crypto is built on Ethereum rather than Bitcoin. Stablecoins, decentralized exchanges, lending protocols, NFTs, and most tokenized real-world assets live on Ethereum or networks designed to be compatible with it. When people talk about decentralized finance or on-chain applications, they are usually talking about things running on Ethereum's model.

Smart contracts and gas

The core innovation is the smart contract, which despite the name is just a program that lives on the blockchain and runs exactly as written, automatically, with no one able to stop or alter it once deployed. A smart contract can hold funds, enforce rules, and interact with other contracts, which is what lets developers build applications, an exchange, a lending market, a game, that run without a company operating them. The code is the operator.

Running these programs costs something, because thousands of computers execute and store the results. That cost is paid in a fee called gas, denominated in ether. The more complex the operation or the busier the network, the more gas it costs, which is why fees rise when Ethereum is in heavy demand. Gas is the mechanism that stops the network from being overwhelmed by free computation and pays the people securing it.

The move to proof of stake

For its first several years Ethereum used mining, like Bitcoin. In 2022, in an upgrade known as the Merge, it switched to a completely different security model called proof of stake. Instead of miners burning energy to compete, validators lock up, or stake, their own ether as a financial guarantee of honest behavior, and they are chosen to confirm blocks in proportion to what they have staked. Misbehave and you lose your stake.

The practical effect was dramatic: the change cut Ethereum's energy consumption by more than 99 percent overnight, addressing the biggest environmental criticism of the network. It also introduced staking as a way for ether holders to earn a yield by helping secure the network, which has become a major part of how the ecosystem works. Proof of stake is now the model most newer blockchains use.

What ether is for

Ether has a few distinct roles, which is part of what makes it different from bitcoin. First and most fundamentally, it is the fuel: you need ether to pay gas and do anything on the network. Second, it is a store of value and investment in its own right, held as a bet on the growth of the Ethereum ecosystem. Third, it can be staked to help secure the network and earn a yield, and fourth, it serves as the base collateral and trading pair across much of decentralized finance.

That bundle of roles leads some to describe ether as a productive asset in a way bitcoin is not, since it can be put to work earning yield and powers an entire economy of applications. Others see that complexity as added risk. Both views are defensible, and which one is right is exactly the kind of thing the market debates.

The risks worth understanding

Ethereum carries Bitcoin's volatility and self-custody risks, plus some of its own that come from being a platform rather than just money. Smart contracts can contain bugs, and because they run automatically and often hold large sums, a flaw can be exploited to drain funds, which has happened many times across the applications built on Ethereum. The risk is usually in the individual application rather than Ethereum itself, but for a user the distinction can be cold comfort.

There is also competition. Other programmable blockchains aim to be faster or cheaper, and whether Ethereum keeps its central position depends on its ongoing upgrades to scale, many of which push activity onto faster layers built on top of it. Add evolving regulation, especially around staking, and the picture is of a powerful, central, but still-maturing platform. As always, this is context, not advice.

Following the Ethereum price

Ether is the second-most-watched price in crypto after bitcoin, and because so much of the ecosystem runs on Ethereum, its price often reflects sentiment about the broader on-chain economy, not just one coin. Many people track bitcoin and ether together as the two anchors of the market.

CoinNotch shows the live Ethereum price in your Mac menu bar so you can follow it at a glance. For tracking it specifically, see Ethereum price in the notch, and to understand a fast competitor, read what is Solana.

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