Secure online transactions are enabled by technologies such as SSL (Secure Sockets Layer) and its successor, TLS (Transport Layer Security). These protocols encrypt data exchanged between users and servers, ensuring confidentiality and integrity during communication. Protocols like HTTPS, which incorporate SSL/TLS, protect sensitive information such as payment details and personal data from interception. The use of these technologies is critical for building trust in online transactions and safeguarding against potential cyber threats.