The technology primarily used for cryptocurrency transactions is blockchain. Blockchain is a decentralized ledger that records all transactions across a network of computers. This ensures transparency and security, as every transaction is verifiable and immutable. It eliminates the need for intermediaries, allowing for faster, peer-to-peer transactions without relying on traditional banks. Popular cryptocurrencies like Bitcoin and Ethereum leverage blockchain technology to provide a secure, transparent means of transferring value. The rise of blockchain has significant implications for various industries, including finance and supply chain management.