Ethereum Made Blockchains Programmable. Here's How the Machine Actually Works

Bitcoin proved a decentralized network could keep a ledger of money without a central authority. Ethereum asked what else that network could do — and its answer, smart contracts, turned blockchains from payment rails into programmable platforms. According to The Block, understanding Ethereum means understanding a handful of ideas: contracts that execute themselves, a virtual machine every node runs, and a fee system that prices every action.

A smart contract is code that lives on a blockchain and automatically carries out predefined actions when conditions are met. The Block offers a vending-machine analogy: insert money, and the machine dispenses the snack with no human in the loop. Contracts like these make decentralized applications — dApps — possible, covering everything from financial services to games, without traditional intermediaries.

Accounts, the EVM, and the cost of doing business

Ethereum tracks balances differently from Bitcoin. Instead of Bitcoin's model of tracking individual transaction outputs, Ethereum uses an account-based model, more like a bank ledger. There are two kinds of accounts, according to The Block: externally owned accounts, controlled by a private key, which can initiate transactions; and contract accounts, controlled by code, which only act when triggered.

The contracts themselves run inside the Ethereum Virtual Machine, or EVM — a shared environment that ensures every node executes the same code the same way. That consistency is what lets thousands of independent computers agree on what a contract did.

Gas fees serve two purposes, The Block explains. They compensate validators for keeping the network running, and they make spam expensive by attaching a cost to every action. Fees are commonly quoted in gwei, a small unit of ETH.

From miners to validators

Ethereum originally ran on Proof of Work, with miners solving computational puzzles. It later switched to Proof of Stake in the upgrade known as The Merge. Under Proof of Stake, validators are selected to create new blocks based on ETH they have staked as collateral, and dishonest behavior can cost them part of that stake through a penalty called slashing.

Changes to the network itself follow a formal process. Ethereum Improvement Proposals, or EIPs, are written documents that move through public review and debate before being implemented as upgrades — blueprints for the network, as The Block describes them.

Why rivals exist at all

Ethereum was one of the first major platforms for smart contracts, but popularity brought congestion and higher fees — and that opened the door to rival Layer 1 chains. Each makes different design choices, optimizing for speed, cost, decentralization, developer experience, or specific use cases.

The common constraint is the blockchain trilemma: the trade-off among decentralization, scalability, and security, where improving two often costs the third. That tension is why scalability is the next frontier. As The Block puts it, a single-lane road works when few people drive, but gridlocks when everyone does — and base-layer blockchains face the same problem as demand grows.

Written by the BidAsk Newsroom. Based on reporting from the sources below.