The primary difference between a blockchain and a traditional bank is that a blockchain provides a distributed ledger, while a traditional bank provides a ledger that the bank itself manages. Even though both a blockchain and a traditional bank provide ledgers that outline the details of transactions, a blockchain's entries come from a network of nodes that solve math puzzles and verifying the answers of others. In this way, a blockchain is decentralized—no single entity has control over it. Also, a blockchain consists of time-stamped computations that you can't change. In other words, they are immutable. No one can go to a block in the blockchain and alter its contents. With a traditional bank, someone with the right credentials can open a computer and change the transaction parameters, making traditional banks vulnerable to thieves and hackers.