A ledger is a record that tracks transactions and shows how value moves within a financial system. This record might be a paper book, a database, or a digital system like a blockchain. In cryptocurrencies, a ledger keeps a lasting history of transfers so anyone can see which accounts hold which assets.
On public blockchains, the ledger is a record of all past transactions. Each new transfer is added to this chain and becomes part of the permanent record. Since every entry links to earlier ones and uses cryptography, it is nearly impossible to change past records. This gives users a single, reliable source for balances and transfers.
Public ledgers allow anyone to read the full history, and in many cases, anyone can help validate new entries. Private ledgers limit access and are managed by a set group of participants. Public ledgers focus on openness and broad verification, while private ledgers offer more control and faster, permissioned processing. Bitcoin and Ethereum are examples of public ledgers.
Digital ledgers gather transactions and group them together. These groups are protected with cryptographic hashes and given a timestamp. A network of computers checks that new transactions follow the rules before accepting them. After a group is added, its data cannot be changed without breaking the cryptographic links. This is why many digital ledgers are called immutable.
Ledgers are useful for many things, like tracking money, proving ownership, auditing activity, and running automated contracts that work when certain conditions are met. In business, ledgers support accounting and reconciliation. In crypto, they let users check balances without a central authority. Some systems use ledgers for public transparency, while others use them for private control.
Keeping a ledger is different from holding the keys that let you move assets recorded on it. If you have the private keys for an account, you can sign transactions to update the ledger for that account. Many people use hardware devices or secure cards to protect these keys, so signatures can be made safely without revealing secrets. This protection helps stop thieves from taking control of funds, even though many people can view the ledger.
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