Blockchain plays a crucial role in secure digital transactions by providing a decentralized and tamper-resistant ledger. Each transaction is recorded in blocks, linked chronologically, and validated through consensus mechanisms, ensuring data integrity. This technology eliminates the need for intermediaries, reducing transaction costs and enhancing transparency. With cryptographic techniques, blockchain secures transaction data and verifies identities without compromising sensitive information. Its applications extend beyond currency transactions to areas like smart contracts and supply chain management, fostering trust and efficiency in digital interactions.