A text encoding for cryptographic objects: Base64-encoded DER wrapped between
-----BEGIN ...----- and -----END ...----- markers. A single PEM file can hold
several objects concatenated, such as a certificate followed by its chain, and is
the default format for OpenSSL and most non-Windows tooling. The label in the
marker line tells you what is inside — CERTIFICATE, CERTIFICATE REQUEST,
PRIVATE KEY and so on.