**Blockchain** is a decentralized digital ledger that stores information in blocks linked together. Each block contains a cryptographic hash of the previous block, making it secure and difficult to manipulate or change data once recorded. Blockchain technology allows for secure, transparent, and tamper-proof transactions without the need for intermediaries like banks.

The most well-known application of blockchain is in cryptocurrencies like Bitcoin, where it ensures secure peer-to-peer transactions. However, blockchain has potential applications in various industries such as supply chain management, healthcare, and voting systems.

Despite its potential benefits, blockchain also faces challenges such as scalability, regulatory issues, and energy consumption. As with any new technology, there is ongoing research and development to address these challenges and further explore the potential of blockchain.