Bitcoin Whitepaper — Annotated Guide

# 3. Timestamp Server

The solution we propose begins with a timestamp server. A timestamp server works by taking a hash of a block of items to be timestamped and widely publishing the hash, such as in a newspaper or Usenet post. The timestamp proves that the data must have existed at the time, obviously, in order to get into the hash. Each timestamp includes the previous timestamp in its hash, forming a chain, with each additional timestamp reinforcing the ones before it.

> 💡 In plain terms
> A "hash" is a fingerprint for data.
> Feed any amount of data into a hash function and you get a short, fixed-length string back. The critical property: even a tiny change to the original data produces a completely different hash.
>
> A timestamp server takes a batch of transactions, hashes them all together, and publishes that hash publicly. This proves those transactions existed at that point in time — because you'd need to know the data before you could produce its hash.
>
> Now here's the clever part: each new block's hash includes the previous block's hash.
> That means every block is mathematically linked to the one before it, all the way back to the very first block (the "genesis block").
>
> This creates a chain. If you tried to go back and change an old transaction, you'd change that block's hash — which would break the link to the next block, and the next, and every block after it. The tampering would be immediately obvious.

> ⚡ Why It Works vs. Traditional Finance
> Banks keep their ledgers in private databases. There is no way for an outsider to independently verify that a record hasn't been quietly altered.
>
> Bitcoin's timestamp chain is the opposite: it's public, and altering any record requires visibly breaking the mathematical links in the chain.
> The older a transaction is, the more blocks have been built on top of it, and the more computational work would be needed to rewrite it.
> History in Bitcoin becomes progressively harder to change — not easier.
> This is the exact opposite of a private database where an administrator can edit records with a few keystrokes.

Bitcoin Timestamp Server

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