A hash is a digital fingerprint created by passing a set of data through a hash function. This function transforms any amount of data, regardless of size, into a unique, compact string of numbers and letters. A small change in the data results in a completely different hash, making it a reliable means of ensuring data integrity.

In the world of blockchain, each added block is connected to its predecessor by this hash function. This ensures that the content of each block, consisting of transaction data, is converted into a unique hash. Any attempt to change data in a block would be noticed immediately, as this would change the hash of both that block and all subsequent blocks in the chain.

This structure is what gives blockchains their immutability and protection against manipulation. Each block in the chain is inextricably linked to its predecessors and successors.

Finally, the Transaction Hash, or Tx Hash, acts as a unique code that identifies each cryptocurrency transaction, confirming that the transaction has been approved and recorded in the blockchain.