Cryptography is a method of protecting data and communications in computer systems. Through codes, cryptography ensures that only those for whom the information is intended can read and process it.

Blockchains are called blockchains because they are a chain of blocks that contain data. The chain is linked together using cryptography. More specifically, each block, when added to the chain, includes a cryptographic 'hash' that locks it into the chain.A cryptographic hash is a set of numbers and letters generated by an algorithm to identify data. Once the hash is created, if the data is tampered with, it destroys the hash, letting everyone know that tampering occurred.The hash included in each new block also identifies the data from the previous block, making for a strong chain. If anyone tampers with the data in one block, the hash is destroyed and all nodes can see that data has been altered so they know not to trust the data from that point onward.In this way, cryptography and hash algorithms keep the data on a blockchain secure, transparent and immutable, creating a solid foundation for trust between participants.