PKCS #12 (Public-Key Cryptography Standards #12) is a file format used to store cryptographic keys, certificates, and other sensitive information in a single, password-protected file. It's commonly used for secure storage and transfer of digital identities, such as those used for email signing, website authentication, and code signing. The PKCS #12 format is a binary format that can contain multiple certificates and private keys, along with any necessary intermediate certificates. The entire file is encrypted with a password, providing a layer of security to protect the sensitive data within. This format is widely supported by various operating systems, browsers, and email clients, making it a standard for managing digital certificates. The .p12 file extension is often used interchangeably with .pfx, as they both represent the same PKCS #12 format. The format is defined by RFC 7292.