Blockchain

Also known as: Distributed Ledger, DLT

A public, append-only ledger replicated across many nodes, secured by cryptography and a consensus mechanism.

Core idea

A blockchain is a list of blocks, where each block contains a batch of transactions plus a cryptographic hash of the previous block. Tampering with any block invalidates every block after it — which is why the ledger is effectively immutable once confirmed.

Key components

Nodes — computers running the protocol, validating transactions.
Consensus — rules that decide which block is «the truth». The two dominant families are Proof of Work (Bitcoin) and Proof of Stake (Ethereum, Solana, Cosmos).
Tokens / coins — the native unit that pays for block space and secures the chain.

Public vs private

Public (BTC, ETH, SOL) — anyone can read, anyone can transact, anyone can run a node.
Private / permissioned — membership gated by an organization. Closer to a shared database than a trustless network.

Why it matters for traders

Blockchain data is public. That is why on-chain metrics like SOPR, MVRV and exchange flows exist — we can literally see supply move.

Frequently asked

Is every crypto on a blockchain?

Almost. A handful of projects use variants (DAGs like IOTA, or L2 rollups that post to an L1), but the vast majority settle on a public blockchain.

Who controls a blockchain?

Public blockchains like Bitcoin and Ethereum are controlled by the network of nodes running the same protocol. Changes require broad consensus.