In blockchain technology, a block is a fundamental data structure that stores a batch of verified transactions. Each block is linked to the previous one, forming a chain of blocks (hence, blockchain).
Key Components of a Block
- Block Header
- Previous Block Hash – A reference to the hash of the prior block.
- Timestamp – When the block was created.
- Nonce – A random number used in mining (Proof of Work).
- Merkle Root – A hash of all transactions in the block.
- Block Body
- Contains the list of transactions.
- Block Hash
- A unique cryptographic fingerprint (e.g., SHA-256 in Bitcoin).
How Blocks Work
- New transactions are grouped into a block.
- Miners (or validators) compete to solve a cryptographic puzzle (PoW) or stake tokens (PoS).
- Once validated, the block is added to the blockchain.
- Changing any block requires altering all subsequent blocks (ensuring security).
Example (Bitcoin Block)
- Block Size: ~1–4 MB (varies).
- Average Time Between Blocks: 10 minutes (Bitcoin).
- Famous Blocks: Genesis Block (Block 0, mined by Satoshi Nakamoto in 2009).
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