Which protocol is commonly used to securely transfer files over the Internet?

SFTP, or Secure File Transfer Protocol, is designed specifically to securely transfer files over the Internet. It operates over a secure connection established through SSH (Secure Shell), which provides a level of data integrity and confidentiality not offered by other protocols. SFTP encrypts both the data and the command channel, ensuring that sensitive information remains protected during transfer.

In contrast, other options such as FTP (File Transfer Protocol) do not provide encryption, making it vulnerable to interception and unauthorized access. HTTP (Hypertext Transfer Protocol), primarily designed for web traffic, also lacks the security features needed for safely transferring files. SMTP (Simple Mail Transfer Protocol) is used for sending emails, not for file transfers. Therefore, SFTP stands out as the appropriate choice for secure file transfer, aligning with the need for encryption and secure handling of sensitive data.