Ethereum: The World Computer

Bitcoin was step one. Ethereum was step two.

Bitcoin proved you could send money without a bank. That was a big deal. But Bitcoin's scripting language is simple on purpose — it handles transfers and not much else.

In 2013, a 19-year-old programmer named Vitalik Buterin published a whitepaper asking: what if a blockchain could run any program, not just money transfers? Two years later, Ethereum launched. It is a blockchain with a built-in computer.

What Ethereum actually is

Ethereum is a network of thousands of computers that all run the same virtual machine. This machine is called the EVM (Ethereum Virtual Machine). Anyone can write a program, deploy it to the EVM, and it will run exactly the same way on every computer in the network.

Think of it like this: Google Docs runs on Google's servers. If Google shuts down, your documents disappear. An Ethereum smart contract runs on thousands of independent computers. No single company can shut it down.

Ethereum vs Bitcoin

Both are blockchains. Both use cryptocurrency. But they serve different purposes.

Feature	Bitcoin	Ethereum
Launched	2009	2015
Purpose	Digital money	Programmable platform
Programming	Very limited scripts	Full smart contracts (Solidity)
Block time	~10 minutes	~12 seconds
Consensus	Proof of Work	Proof of Stake (since Sept 2022)
Native token	BTC	ETH
Main use	Store and send value	Run decentralized applications

Bitcoin is digital gold. Ethereum is a decentralized computer that happens to have its own currency.

How smart contracts work on Ethereum

A smart contract is a program stored on the Ethereum blockchain. Once deployed, it cannot be changed. It runs exactly as written, every time.

Here is what happens when you interact with one:

You send a transaction to the contract's address (like calling a function)
Every node on the network executes the contract code in their EVM
All nodes arrive at the same result (because the EVM is deterministic)
The result is recorded on the blockchain

Every operation the EVM performs costs gas. Simple operations (addition, comparison) cost a little gas. Complex operations (storing data on-chain) cost more. You pay for gas in ETH.

The token standards

Ethereum introduced token standards — templates for creating digital assets. The two most important ones:

ERC-20 is for fungible tokens (every token is identical). USDC, UNI, LINK, and thousands of other tokens use this standard. Think of them like currencies — one USDC is the same as any other USDC.

ERC-721 is for non-fungible tokens (NFTs). Each token is unique. A CryptoPunk NFT is different from every other CryptoPunk. Think of them like concert tickets — each one has a unique seat number.

Because these are standards, any ERC-20 token works with any wallet, any exchange, and any DeFi protocol. This interoperability is one of Ethereum's biggest strengths.

Ethereum's numbers

Some facts about the network today:

Validators: Over 1 million active validators secure the network
Staking requirement: 32 ETH per validator
Block time: 12 seconds
Transactions per day: Over 1 million
Smart contracts deployed: Millions (most are inactive)
Total value locked in DeFi: Tens of billions of dollars

What Ethereum cannot do (yet)

Ethereum has real limits:

Speed: 12 seconds per block, ~15-30 transactions per second on the main chain. Visa handles ~1,700 per second. This is why Layer 2 networks exist — they process transactions off the main chain and settle back to Ethereum periodically.

Cost: During busy periods, a simple token swap can cost $5-50 in gas fees. Layer 2 networks reduce this to pennies.

Storage: Storing data on-chain is expensive. That is why NFT images are usually stored on IPFS (a decentralized file system), not directly on Ethereum.

Key takeaways

Ethereum is a blockchain with a built-in computer (the EVM) that can run programs called smart contracts.
Smart contracts are permanent, unstoppable, and run exactly as written.
Every operation costs gas, paid in ETH.
ERC-20 (fungible tokens) and ERC-721 (NFTs) are the two main token standards.
Ethereum is slow and expensive on its own, which is why Layer 2 networks exist.