Blockchain Technology

Blockchain technology is a distributed digital ledger that records transactions across multiple computers in a way that makes the records tamper-resistant. Each transaction is grouped into a block, and blocks are chained together in chronological order, creating a permanent, transparent, and decentralised record.

What Is Blockchain?

A blockchain is essentially a shared database maintained by a network of computers (nodes) rather than a central authority. When a new transaction occurs:

1. It is broadcast to the network
2. Nodes verify the transaction using a consensus mechanism
3. The verified transaction is grouped with others into a block
4. The block is added to the existing chain with a cryptographic link to the previous block
5. The record becomes permanent and visible to all network participants

Key Properties of Blockchain

– **Decentralised**: no single entity controls the ledger; thousands of nodes hold copies
– **Immutable**: once recorded, transactions cannot be altered without changing all subsequent blocks and gaining network consensus
– **Transparent**: all network participants can view the full transaction history (in public blockchains)
– **Cryptographically secured**: each block contains a hash of the previous block, making tampering detectable

Types of Blockchains

– **Public blockchain**: open to anyone; Bitcoin and Ethereum are examples; fully decentralised
– **Private blockchain**: access restricted to authorised participants; used by enterprises and governments
– **Consortium blockchain**: controlled by a group of organisations; common in banking and supply chains

Applications Beyond Cryptocurrency

– **Finance**: cross-border payments, trade finance, digital assets
– **Supply chain**: tracking goods from manufacturer to consumer
– **Healthcare**: secure sharing of patient records
– **Government**: land records, voting, identity management

Practical Example

The Indian state of Telangana explored blockchain for land records. Each property transaction is recorded on a blockchain, creating a tamper-resistant ownership history. This prevents fraud, makes title searches faster, and reduces disputes.

Key Takeaways

– Blockchain is a distributed, tamper-resistant ledger maintained across multiple computers without a central authority
– Transactions are grouped into blocks and chained cryptographically, making manipulation detectable
– Public blockchains (like Bitcoin) are open to all; private and consortium blockchains are permissioned
– Applications extend beyond crypto to land records, supply chains, healthcare, and financial services
– In India, blockchain is being explored for UPI settlements, government record-keeping, and digital identity