Blockchain technology extends far beyond cryptocurrency into enterprise applications. A blockchain is a distributed ledger where data is stored in blocks linked cryptographically. Each block contains a timestamp, transaction data, and a hash of the previous block. Consensus mechanisms like Proof of Work and Proof of Stake validate new blocks. Smart contracts are self-executing contracts with terms directly written in code. Ethereum popularized smart contracts for decentralized applications (dApps). Supply chain from blockchain's immutable audit trail. Healthcare can securely share patient records across providers. Real estate transactions become more transparent with blockchain recording. Digital identity verification gains security through blockchain. Intellectual property rights can be tracked and enforced automatically. Voting systems could become more secure and transparent. Challenges include scalability, energy consumption, and regulatory uncertainty. Layer 2 solutions like Lightning Network address scalability. Permissioned blockchains like Hyperledger serve enterprise needs. Non-fungible tokens (NFTs) have applications beyond art, including ticketing and certification. Decentralized finance (DeFi) is disrupting traditional banking. Understanding blockchain's fundamentals enables identifying real use cases beyond speculation.