Blockchain

A blockchain is a shared, append-only digital ledger that records transactions across a distributed network of computers. Once data is confirmed and bundled into a “block,” that block is cryptographically linked to the one before it, forming a chain. Altering an old record would mean re-computing every block that followed it on a majority of the network at once, which is what makes the history tamper-resistant.

How it works

Each participant, or node, keeps a copy of the ledger. When someone broadcasts a transaction, the network groups pending transactions into a candidate block and uses a consensus mechanism — such as proof of work or proof of stake — to agree on which block is added next. After a block is accepted, every honest node updates its copy, so all participants share a single, consistent version of events without needing a central authority.

Why it matters

Blockchains let parties who do not trust one another agree on a common record. That property underpins cryptocurrency, but the same idea is applied to supply-chain tracking, digital identity and tokenized real-world assets. The trade-off is that decentralization and security usually come at the cost of raw throughput, which is the problem that Layer 2 scaling networks try to address.

Example

When you send Bitcoin, your transaction joins a block that miners compete to confirm. After confirmation it becomes part of the permanent chain, viewable by anyone running a node or using a public block explorer.