What Is Blockchain
Last updated: March 31, 2026
Key Facts
- Each block contains a cryptographic hash of the previous block, creating an unbreakable chain
- Bitcoin, launched in 2009, was the first major application of blockchain technology
- Blockchain eliminates the need for trusted intermediaries like banks for verifying transactions
- Smart contracts on blockchains like Ethereum can execute agreements automatically
- Over 80 countries are exploring central bank digital currencies (CBDCs) using blockchain concepts
Overview
A blockchain is essentially a shared database that differs from a traditional database in how it stores information. Instead of storing data in tables, blockchains store data in blocks that are chained together chronologically. Each block has a limited storage capacity — when filled, it is closed and linked to the previously filled block, forming a chain of data.
How Blockchain Works
When a new transaction occurs, it is broadcast to a peer-to-peer network of computers (nodes). These nodes validate the transaction using known algorithms. Once verified, the transaction is combined with other transactions to create a new block of data for the ledger. This new block is then added to the existing blockchain in a way that is permanent and unalterable.
Key mechanism: Each block contains its own hash (a unique digital fingerprint), the hash of the previous block, and the transaction data. If anyone tries to alter a block, its hash changes, breaking the chain — making tampering immediately detectable.
Types of Blockchain
- Public blockchains like Bitcoin and Ethereum are open to anyone and fully decentralized
- Private blockchains restrict access to authorized participants, used by enterprises
- Consortium blockchains are governed by a group of organizations rather than one entity
Beyond Cryptocurrency
While blockchain is best known for powering cryptocurrencies, its applications extend far beyond digital money. Supply chain tracking, digital identity verification, voting systems, healthcare records, and intellectual property management all benefit from blockchain's transparency and immutability.
Related Questions
Is blockchain the same as Bitcoin?
No. Bitcoin is a cryptocurrency that uses blockchain technology, but blockchain itself is a broader technology with many applications beyond cryptocurrency, including supply chain management, voting systems, and digital identity verification.
Can blockchain be hacked?
While the blockchain itself is extremely difficult to hack due to its distributed and cryptographic nature, the surrounding ecosystem (exchanges, wallets, smart contracts) can be vulnerable. A 51% attack is theoretically possible but impractical on large networks like Bitcoin.
Why does blockchain use so much energy?
Proof-of-Work blockchains like Bitcoin require miners to solve complex mathematical puzzles, consuming significant electricity. However, many newer blockchains use Proof-of-Stake, which reduces energy consumption by over 99%. Ethereum switched to Proof-of-Stake in 2022.
Sources
- Wikipedia — Blockchain CC-BY-SA-4.0
- Investopedia — Blockchain Explained fair_use