Blockchain is a decentralized digital ledger technology that records transactions across multiple computers in a way that ensures security and transparency. Each transaction is grouped into a block, which is linked to the previous one in a chronological chain, making it tamper-proof. Once recorded, the information is immutable and can be verified by network participants, reducing the risk of fraud. By eliminating the need for intermediaries, blockchain enhances efficiency, lowers costs, and increases trust in various applications, including cryptocurrencies, supply chain management, and smart contracts.