Beginner Track 03
Blocks form a chain
Each block stores the hash of the previous block (Prev Hash). That single field links every block into an unbreakable chain.
What you'll learn
- → How Prev Hash links blocks into a chain
- → Why tampering with one block invalidates everything after it
- → Forks and the longest-chain rule (Nakamoto Consensus)
prevHash = 4a3f8c21...
prevHash = b92e7f43...
prevHash = c5d1a809...
💡 Why is the chain immutable?
Changing Block #1's data changes its hash. Then Block #2's Prev Hash no longer matches → Block #2 invalid. Block #2's hash must also change → Block #3 Prev Hash mismatch → Block #3 invalid. To alter any block you must re-mine every block that follows.