S/MIME, or Secure/Multipurpose Internet Mail Extensions, is a standard for public key encryption and signing of email messages. It allows users to send secure emails by encrypting the content, ensuring that only the intended recipient can read it. S/MIME also enables digital signatures, which verify the sender's identity and confirm that the message has not been altered during transmission. To use S/MIME, both the sender and recipient must have S/MIME-compatible email clients and digital certificates issued by a trusted certificate authority. This technology enhances email security, making it a popular choice for organizations that prioritize confidentiality and data integrity in their communications.