What is Blockchain Technology?
Blockchain is a distributed ledger technology that links data blocks in chronological order using cryptographic methods, enabling decentralized data storage and verification.
Core Features
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Decentralization
- No single control node; data is distributed across all nodes in the network
- Each node maintains a complete copy of the ledger
- Eliminates single points of failure
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Immutability
- Once data is written to a block, it is virtually impossible to modify
- Hash pointers and consensus mechanisms ensure data integrity
- Any tampering would change the hash values of all subsequent blocks
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Transparency
- All transaction records are publicly visible to network participants
- Every node can verify the validity of transactions
- Increases system trustworthiness
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Security
- Uses cryptographic techniques to protect data
- Consensus mechanisms prevent malicious attacks
- 51% attacks are extremely difficult to execute
Decentralization Principles
Traditional Centralized System: User → Central Server → Database Blockchain Decentralized System: UserA → Node Network ← UserB ↓ ↓ ↓ Node1 Node2 Node3 ↓ ↓ ↓ Complete Ledger Copy (Distributed Storage)
Workflow
- Transaction Initiation: User creates and broadcasts a transaction
- Transaction Verification: Network nodes verify transaction validity
- Block Packaging: Miners/validators package transactions into blocks
- Consensus Achievement: Network confirms blocks through consensus mechanisms
- Block Addition: New blocks are added to the chain and synchronized across the network
Application Scenarios
- Cryptocurrencies (Bitcoin, Ethereum)
- Supply chain management
- Digital identity authentication
- Smart contracts
- Decentralized Finance (DeFi)
Interview Key Points
- Understand the difference between distributed ledgers and centralized databases
- Master the role of hash functions in blockchain
- Understand the pros and cons of different consensus mechanisms
- Be able to explain the Byzantine Generals Problem and its solutions