Protocols commonly used for secure data transmission over the web include HTTPS (HyperText Transfer Protocol Secure) and SSL/TLS (Secure Sockets Layer/Transport Layer Security). HTTPS encrypts data exchanged between the client and server, safeguarding it from eavesdropping and tampering. SSL/TLS establishes a secure, encrypted link and ensures that user data remains confidential and integrity is maintained. These protocols are crucial for protecting sensitive information, such as personal data and financial transactions, during online interactions.