A private blockchain is a permissioned ledger where access is restricted to authorized participants. Unlike public blockchains like Ethereum, private blockchains are used by businesses for internal use cases such as supply chain management, record-keeping, and secure data sharing. They offer greater control over data privacy, faster transaction speeds, and enhanced scalability. Popular platforms include Hyperledger Fabric and R3 Corda. Enterprises choose private blockchains to benefit from blockchain's security and transparency while maintaining confidentiality and meeting regulatory compliance.