A public ledger

A blockchain is a shared record of transactions that thousands of computers keep in sync. Once a transaction is added, it can't be quietly edited or removed. On networks such as Bitcoin and Ethereum, anyone can look up any transaction, at any time.

That permanence is what makes tracing possible. When crypto is lost to fraud, the record of where it went doesn't disappear.

Blocks and confirmations

Transactions are grouped into blocks. Each block points back to the one before it, which is where the name comes from. When a transaction is included in a block, it's "confirmed". More blocks on top make it harder to reverse, which is also why a crypto payment usually can't be cancelled.

Different chains, different rules

There isn't one blockchain. Bitcoin, Ethereum, TRON and others each keep their own ledger. Funds can move between them through services called bridges, which is one reason a trace sometimes crosses several chains.

What a blockchain doesn't show

A blockchain shows addresses and amounts, not names. Linking an address to a person or a company needs other information, such as an exchange's customer records. That's why investigators work with the services that hold those records, and why only police and courts can require them to act.

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