Blockchain is a way for a network of independent computers to maintain a shared record without relying on a single database operator. The term describes a family of distributed-ledger designs rather than one product or one cryptocurrency.

Educational scope. This guide explains technology and terminology. It does not offer investment advice, trading signals, wallet services, exchange services, staking services or projected financial returns.

What you'll understand

  • In a conventional database, one organization normally controls the servers and decides which updates are accepted.
  • Many blockchains collect valid transactions into batches called blocks.
  • Nodes are computers that participate in the network.
  • BTC and ETH are native assets of the Bitcoin and Ethereum networks respectively.

A shared record maintained by many computers

In a conventional database, one organization normally controls the servers and decides which updates are accepted. A public blockchain distributes parts of that job across a network of nodes. Nodes receive data, check it against protocol rules and keep their own copy of the ledger.

The ledger is not automatically trustworthy simply because it is distributed. Trust comes from transparent rules, cryptographic verification, economic incentives and the ability of many independent participants to compare the same history.

Why transactions are grouped into blocks

Many blockchains collect valid transactions into batches called blocks. A block usually includes a reference to an earlier block, which helps create an ordered history. Changing an old record would therefore require changing the surrounding cryptographic history and, on major public networks, overcoming the network's consensus process.

Different networks use different block sizes, timing rules and data structures. The word blockchain is useful at a high level, but the implementation details matter when comparing Bitcoin, Ethereum and other systems.

Nodes, validators and consensus

Nodes are computers that participate in the network. Some simply verify and relay data; others may propose blocks or take part in consensus. In proof-of-work systems, miners compete using computation. In proof-of-stake systems, validators participate under protocol-defined staking rules.

Consensus does not mean every participant votes on every transaction. It means the network has a method for agreeing on which valid history should be treated as canonical when several possibilities exist.

Public blockchains and digital assets

BTC and ETH are native assets of the Bitcoin and Ethereum networks respectively. Other assets, such as USDT, can exist as tokens on one or more blockchains. The fact that an asset uses blockchain infrastructure does not by itself explain its legal status, financial risk or suitability for any person.

This academy discusses these systems as technology. It does not provide instructions for buying, selling or investing in digital assets.

Key takeaway

The clearest way to understand this topic is to separate the protocol, the digital asset, the software interface and any third-party service. Each layer has different responsibilities, dependencies and risks.