Hash functions are mathematical algorithms that convert input data of any size into fixed-length output strings (hash values). Key Properties:
Deterministic: Same input always produces same output
Avalanche Effect: Small input change drastically changes output
One-way: Computationally infeasible to reverse
Collision Resistant: Nearly impossible to find two inputs with same output Blockchain Applications: Block Linking: Each block contains hash of previous block, creating an immutable chain. Transaction Integrity: Merkle trees use hashes to efficiently verify transaction data. Mining: PoW consensus requires finding hashes meeting difficulty targets. Address Generation: Public keys are hashed to create wallet addresses. Example (SHA-256):
