Timestamp Server

A timestamp server is the idea at the heart of Bitcoin's design: a system that takes a batch of data, hashes it, and publishes the hash widely so anyone can later prove the data existed at that moment. Satoshi Nakamoto's whitepaper describes a blockchain as a distributed timestamp server, where each block's hash covers the previous one and so extends a chain of proof stretching back to the first block. Because rewriting an old entry would require redoing all the work that followed, the ordering of transactions becomes practically settled. The point is ordering, not clock accuracy: block timestamps are approximate and can drift within protocol limits, so they should never be treated as precise time evidence.