A shared ledger, in order
A blockchain is a shared ledger. Each block holds a batch of transactions and a link — a hash — to the block before it. Height is the block’s position in that sequence. The time you see above is the stamp recorded when that block was produced. It keeps order and helps the network reject conflicting spends.
The snapshot is the public chain tip when our data source responds. It is a teaching prop, not a node you are running, and not a guarantee that we are always in sync with every view of the network.
Why the hash link matters
A hash is a fingerprint of data. Change the data, and the fingerprint changes. Because each block stores the previous fingerprint, editing an old block would make the next block’s stored link wrong — and the one after that, and so on. That is tamper evidence. It is not the same as “unhackable.” It means silent rewriting of history is expensive and visible if the rest of the network still has the original chain.
We keep a six-block teaching chain that uses short toy hashes so you can see genesis, prev IDs, and arrows without reading a 64-character header. Those are not live Bitcoin headers and they do not pay coins.
Height, time, and the tip
Height counts how many blocks have been added since genesis. Time is the stamp the miner put on that block — useful for ordering, not a perfect wall clock. The tip is the latest block this data source has. Different viewers can be a block behind or ahead for a moment. That is normal. It is not the same as “the chain forked and your coins vanished.”
The hash on this page is the fingerprint of the tip header. You do not need to memorize it. Notice that it is long, hex, and useless to type by hand — wallets and explorers exist because of that.
What the chain does not decide by itself
A ledger can record a theft as faithfully as a gift. Finality on the chain is not the same as a fair outcome. Identity, consumer protection, and tax reporting live in the legal world, not in the hash.
Different networks use different rules to decide the next block. Bitcoin uses proof of work. Other networks use other methods. This lesson is about the linked-record idea, not a tour of every consensus slogan.
Why people use a public chain
- Transparency — participants can inspect the same record.
- Tamper evidence — changing one block breaks the hash chain.
- No single operator — no one office has to clear every transfer.
- Common experiments — payments, traces, and other records. Experiments fail. That is allowed in a classroom and costly with real funds.
How this ties to BitBuddy
After you can say “height, hash, previous block” out loud, play the mining game: you will search for a hash that starts with enough zeros. That search is the “work” in proof of work. Then come risk and paper practice — still on this site, still not a brokerage.