What is Ethereum? ETH, Smart Contracts & DeFi Explained

October 15, 2026  ·  7 min read

Ethereum is the world's second-largest cryptocurrency by market cap — but it is much more than a currency. Launched in 2015 by Vitalik Buterin and a team of developers, Ethereum introduced the concept of a programmable blockchain: a global computer that can run code in a decentralized, tamper-resistant way. That single innovation gave rise to DeFi, NFTs, DAOs, and thousands of tokens — all built on top of Ethereum.

How Ethereum Differs from Bitcoin

Bitcoin was designed to do one thing excellently: transfer value from person to person without a middleman. Ethereum was designed to go further — to execute arbitrary programs called smart contracts on a decentralized network.

Think of Ethereum as a world computer: anyone can deploy an application to it, and it runs exactly as programmed without the possibility of downtime, censorship, or fraud — because thousands of nodes worldwide all run and verify the same code simultaneously.

What Are Smart Contracts?

A smart contract is a program stored on the blockchain that automatically executes when predefined conditions are met. No intermediary, no manual enforcement. Examples:

• A lending protocol that automatically liquidates collateral when a loan-to-value ratio is breached
• A token sale that releases funds to a project only after a funding target is reached
• A decentralized exchange that swaps tokens according to a mathematical formula

The Ethereum Virtual Machine (EVM) is the runtime environment for all smart contracts. Every node runs the EVM, executes every contract, and reaches the same result — that consensus is what makes the system trustless.

Gas Fees and Gwei

Every operation on Ethereum consumes gas — a unit measuring computational work. Users pay gas fees in ETH (denominated in gwei, where 1 gwei = 0.000000001 ETH). Fees fluctuate with network demand.

Since the EIP-1559 upgrade (August 2021), a portion of every gas fee is burned (removed from circulation) rather than paid to validators. During periods of high demand, more ETH is burned than created — making Ethereum deflationary at peak usage.

The Merge: Ethereum Goes Proof of Stake

In September 2022, Ethereum completed "The Merge" — transitioning from energy-intensive Proof of Work mining to Proof of Stakevalidation. The impact was dramatic: Ethereum's energy consumption dropped by over 99.9%. Validators now stake 32 ETH to participate in block production, earning rewards for honest behavior and risking "slashing" (losing staked ETH) for malicious behavior.

ERC-20 and ERC-721: Token Standards

Ethereum's most consequential contribution to crypto is its token standards:

• ERC-20: The standard for fungible tokens. USDT, USDC, LINK, UNI, SHIB — thousands of tokens use this standard, enabling them to work seamlessly with any Ethereum wallet or exchange.
• ERC-721: The standard for non-fungible tokens (NFTs). Each token is unique and provably scarce — the basis for digital art, collectibles, and in-game assets.

Major Ethereum Use Cases

• DeFi (Decentralized Finance): Protocols like Uniswap (DEX), Aave (lending), Curve (stablecoin swaps), and Compound (yield) collectively manage tens of billions in assets — with no central company controlling them.
• NFTs: OpenSea, Blur, and other NFT marketplaces run on Ethereum, enabling provable digital ownership.
• DAOs (Decentralized Autonomous Organizations): Community-governed protocols where token holders vote on decisions using smart contracts.
• Layer 2 networks: Arbitrum, Optimism, and Base scale Ethereum by processing transactions off-chain and settling on Ethereum — reducing fees by 10–100×.

How to Exchange Ethereum

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