Blockchain
Understand the technology that powers cryptocurrency — what a blockchain is, how it works, and the major networks shaping the industry.
A blockchain is a distributed digital ledger that records transactions across a network of computers in a way that is transparent, secure and extremely difficult to alter. Instead of relying on a single central authority like a bank, a blockchain is maintained by many participants who collectively verify and store the same data. This breakthrough is what makes cryptocurrencies possible, but blockchain technology now extends far beyond money into areas like finance, gaming, identity and supply chains.
How a Blockchain Works
Transactions are grouped into blocks, and each new block is cryptographically linked to the one before it, forming a chain. Once a block is confirmed and added, changing it would require altering every subsequent block across the majority of the network simultaneously — a practically impossible feat on a large, well-secured chain. Networks reach agreement on which transactions are valid through a consensus mechanism. The two most common are Proof of Work, where miners compete to solve cryptographic puzzles, and Proof of Stake, where validators are chosen based on the amount of cryptocurrency they lock up as a stake.
Key Concepts
Decentralization
No single entity controls the network, making it resistant to censorship and single points of failure.
Immutability
Once recorded and confirmed, data is practically impossible to change or delete.
Smart Contracts
Self-executing programs that run on the blockchain and automate agreements without intermediaries.
Consensus
The rules and process by which the network agrees on the valid state of the ledger.
Major Blockchains
Bitcoin
The first and most secure blockchain, designed primarily as a decentralized store of value and payment network, secured by Proof of Work.
Ethereum
The leading smart-contract platform, powering most decentralized applications, DeFi and NFTs, and secured by Proof of Stake.
Layer-1 Alternatives
Networks such as Solana, Avalanche, Cardano and others compete to offer high throughput and low fees for applications and payments.
Layer-2 Networks
Scaling solutions built on top of base chains (especially Ethereum) that process transactions faster and more cheaply while inheriting the security of the underlying network.
Why Blockchain Matters
Blockchain enables people to transact and coordinate without trusting a central intermediary. This opens the door to financial services for the unbanked, transparent record-keeping, programmable money, digital ownership and new business models. While the technology is still maturing and faces challenges around scalability, energy use and regulation, it represents one of the most significant shifts in how value and information move online.
Explore blockchain guides in depth
Dive into specific networks and concepts.