1. What is Blockchain?
Blockchain is a digital ledger stored across multiple computers. Each piece of information (transaction) is recorded as a block, and blocks are linked together into a chain.
Imagine a digital notebook that everyone can see, but no one can secretly edit.
2. Why is Blockchain special?
No need for intermediaries: like banks, payment companies…
High security: thanks to cryptography.
Fraud-resistant: altering one block affects the whole chain → easily detected.
Transparent & trustworthy: open for public verification.
3. How does Blockchain work?
A transaction happens (A sends money to B).
The transaction is verified by the network (nodes).
The transaction is bundled into a new block.
The block is encrypted (hashed) and added to the chain.
The updated chain is shared with the entire network.
4. Types of Blockchain
Public Blockchain: open to everyone (Bitcoin, Ethereum).
Private Blockchain: restricted to specific members (enterprise use).
Consortium Blockchain: managed by a group of organizations.
Hybrid Blockchain: mix of public and private.
5. Applications of Blockchain
Cryptocurrencies: Bitcoin, Ethereum…
Smart Contracts
Supply Chain Management
Electronic Voting
Identity Management
Blockchain Games / NFT
6. Strengths and Limitations
Advantages:
Transparency
Security
Fraud prevention
No intermediaries
Limitations:
Slower transaction speed compared to centralized systems
Scalability challenges
High energy consumption (especially with PoW like Bitcoin)
7. Core Concepts to Remember
Block: a unit of data
Chain: a sequence of blocks
Hash: unique identifier of a block
Node: a computer in the network
Consensus: agreement mechanism (PoW, PoS…)
Smart Contract: code that runs on blockchain
Conclusion:
Blockchain is a digital, decentralized, and immutable ledger secured by cryptography, used to store and verify information transparently without intermediaries.
