Blockchain

Definition

A blockchain is a distributed, append-only ledger in which data is grouped into cryptographically linked blocks, replicated across many independent computers so that no single party can unilaterally alter the recorded history.

Overview

A blockchain works by bundling transactions into blocks, each of which includes a cryptographic hash of the previous block, forming an immutable chain. Because every participant in the network holds a copy of the ledger, changing a past record would require rewriting every subsequent block on a majority of nodes simultaneously — which is what makes the structure tamper-resistant rather than tamper-proof. Networks agree on the valid chain state through a consensus algorithm, most famously proof-of-work as used by Bitcoin, or newer alternatives like proof-of-stake used by Ethereum. These mechanisms let mutually distrusting parties agree on a single shared history without a central coordinator. While the technology first became widely known through cryptocurrency, the same architecture underpins smart contracts, decentralized applications, and the broader Web3 ecosystem, extending blockchains from simple payment ledgers into general-purpose, programmable infrastructure.

Key Concepts

• Append-only, cryptographically linked blocks that make historical tampering computationally impractical
• Peer-to-peer replication across many independent nodes with no central server
• Consensus algorithms (proof-of-work, proof-of-stake, and others) to agree on a single valid chain
• Public or permissioned network models depending on who may read or write data
• Transparent, auditable transaction history visible to network participants
• Programmability via smart contracts on platforms that support them
• Resistance to a single point of failure due to decentralization

Use Cases

Frequently Asked Questions

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