Definition
A blockchain is a shared, distributed, and permanent database shared among multiple nodes on a computer network.
State Management & Nodes
historically traceable same as the linkedList
Genesis State: The initial state of the blockchain
Decentralization
the blockchain is a decentralized network mainly because storing data in a peer to peer network of nodes.
Useful blockchain demo
Each block contains the traction data. To some extends, Block = blockNum + nonce + data. Generate one unique hash number.
For Safety Consideration, If blockA hash change, blocks after blockA all gonna change.
And meanwhile distributed blockchain has the mechanism of democracy to ensure each block can not be modified by attacker.