P12
PKCS #12
A file format that bundles a private key with its certificate chain, usually password protected.
A PKCS #12 file, commonly seen with a .p12 or .pfx extension, packages a private key together with its certificate and any intermediate certificates in a single password-protected container. It is the usual way to back up or move a key pair between systems, for example installing a client certificate on a new device. Because it holds the private key, the file must be protected with a strong passphrase and handled carefully. On the exam, contrast P12, which contains the private key, with formats like PEM or DER that may carry only the public certificate.
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