Ethereum Explained: The Platform Behind Most of Web3

Proposed in 2013 by programmer Vitalik Buterin and launched in 2015, Ethereum is an open, decentralized computing platform. Where Bitcoin was designed primarily as digital money, Ethereum was designed as a general-purpose platform on which developers can deploy programs — smart contracts — that run exactly as written, without intermediaries. Most of what people call Web3 today is built on Ethereum or on networks compatible with its design.

Accounts: The Two Fundamental Types

Ethereum's state is made up of accounts, of which there are two kinds:

• Externally owned accounts (EOAs) — controlled by a private key held by a person. These can initiate transactions and are the basis of every wallet, including MetaMask.
• Contract accounts — controlled by the code of a deployed smart contract. They hold funds and execute logic but cannot initiate transactions on their own; they only act when called.

Every account has an address, a balance (denominated in ETH), and — for contracts — persistent storage. This simple model underpins tokens, DeFi protocols, NFTs, and decentralized organizations.

Gas: Paying for Computation

Every operation on Ethereum — transferring ETH, deploying a contract, executing a function — consumes computational resources across thousands of nodes. Gas is the metering system that prices this work:

• Each operation costs a fixed amount of gas units depending on its complexity.
• The sender sets a gas price (base fee determined by network demand, plus an optional priority tip to miners/validators) paid per unit of gas.
• The total fee is gas used multiplied by the gas price, paid in ETH. Unspent gas from a transaction's limit is refunded; operations that run out of gas revert entirely, but the fee is still consumed.

Gas serves two purposes: it prevents infinite loops and spam by making computation costly, and it rewards the validators that secure the network.

Ether (ETH) and Its Roles

Ether is Ethereum's native asset. It serves as:

• Fuel — the asset used to pay gas fees for every transaction.
• Collateral — validators lock ("stake") ETH to participate in securing the network under proof of stake.
• A unit of account and medium of exchange — used across DeFi and NFT marketplaces, and tracked in most token trading pairs.

The Ethereum Virtual Machine

The EVM is the runtime environment in which all smart contracts execute. Its key property is determinism: every node processes the same transactions in the same order and arrives at identical results. The EVM's instruction set is deliberately limited — contracts cannot access the internet, generate randomness securely, or read files — which keeps consensus reproducible. Languages such as Solidity and Vyper compile down to EVM bytecode. Because the EVM became the de facto standard, a family of "EVM-compatible" networks (Polygon, Arbitrum, Optimism, Avalanche, and others) can run the same contracts and share tooling.

Scaling: Layer 2 and the Roadmap

Ethereum's base layer intentionally prioritizes decentralization and security over raw throughput — a design choice that limits it to roughly tens of transactions per second and makes fees volatile. The ecosystem's scaling strategy is to move execution to Layer 2 networks:

• Rollups execute transactions on a separate chain, compress the results, and post them back to Ethereum, inheriting its security while dramatically increasing capacity and lowering fees.
• Optimistic rollups assume transactions are valid and allow a challenge window during which fraud can be proven.
• Zero-knowledge (ZK) rollups submit cryptographic proofs that batches of transactions are valid, verified directly on Ethereum.

Since September 2022 ("The Merge"), Ethereum itself has run on proof of stake, replacing energy-intensive mining with validator staking and reducing new ETH issuance substantially.

What Runs on Ethereum

• DeFi — decentralized exchanges, lending markets, and stablecoin infrastructure (see DeFi basics).
• NFTs — digital collectibles, art, game items, and credential-like tokens (see what are NFTs).
• DAOs — internet-native organizations governed by token-holder voting.
• Stablecoins — the majority of dollar-pegged tokens in the crypto economy are ERC-20 contracts on Ethereum.

Strengths and Limitations

• Strength: the largest developer ecosystem and deepest liquidity in the industry. Limitation: that demand translates to congestion and high fees on the base layer.
• Strength: open, permissionless innovation. Limitation: the same openness enables scams, exploits, and unaudited code, with no recourse for users.
• Strength: credible neutrality — no single company controls the protocol. Limitation: governance upgrades are slow and coordination-heavy.

Conclusion

Ethereum's contribution was to generalize the blockchain from a single-purpose currency into a shared world computer with a programmable settlement layer. Accounts and gas price every action; the EVM guarantees that every participant computes identical results; and Layer 2 networks extend that foundation to far greater scale. Whether any individual project built on it succeeds or fails, Ethereum's architecture — replicated by dozens of compatible chains — defines the technical grammar of modern Web3.