Research on blockchain digital currencies and decentralized immutable ledgers focuses on the development, operation, and evaluation of cryptocurrencies and distributed ledger technologies that enable secure, transparent, and tamper-resistant financial transactions. Studies explore consensus mechanisms, transaction throughput, scalability solutions, and cryptographic techniques that ensure the integrity and immutability of ledger records. Research also investigates privacy-preserving methods, regulatory compliance, and economic models governing digital currencies, including tokenomics and incentive structures. Furthermore, decentralized ledgers are analyzed for applications beyond finance, such as supply chain management, healthcare, and digital identity, highlighting their potential to transform data management and trust in distributed systems. Overall, blockchain digital currencies and immutable ledgers provide a foundation for secure, decentralized, and transparent ecosystems across multiple domains.