Blockchain technology is a decentralized, digital ledger that records transactions across many computers in a way that ensures the data cannot be changed or tampered with.
🧱 Simple Definition:
A blockchain is like a digital notebook shared across a network, where each page (block) contains a list of transactions. Once a page is full, it’s sealed and linked to the previous page — forming a secure chain.
🔑 Key Features:
| Feature | Description |
|---|---|
| Decentralized | No single person or company controls the data — it’s managed by a network. |
| Immutable | Once data is added, it can’t be changed or deleted. |
| Transparent | All transactions are publicly visible and verifiable. |
| Secure | Uses cryptography to protect data and verify transactions. |
⚙️ How It Works (in simple steps):
- Someone requests a transaction (e.g., sending Bitcoin).
- The transaction is broadcast to a network of computers (nodes).
- These nodes verify the transaction using consensus algorithms (e.g., Proof of Work, Proof of Stake).
- Verified transactions are grouped into a block.
- The block is added to the chain permanently and publicly.
🧩 Where Blockchain Is Used:
- Cryptocurrencies (Bitcoin, Ethereum)
- NFTs (digital ownership)
- Supply chain tracking
- Smart contracts
- Voting systems
- Digital identity
🛠️ Popular Blockchains:
| Blockchain | Use Case |
|---|---|
| Bitcoin | Digital currency |
| Ethereum | Smart contracts & dApps |
| Solana | Fast, scalable apps & DeFi |
| Polygon | Ethereum scaling & low-fee apps |