PEM (Privacy-Enhanced Mail) files are a common file format for storing cryptographic keys, certificates, and other data. Despite the name, which originates from an obsolete email encryption standard, PEM files are widely used today, particularly in the context of SSL/TLS for web servers, email security, and other secure communication protocols. A PEM file is essentially a text file that contains Base64 encoded data, typically enclosed between "BEGIN" and "END" boundary markers (e.g., -----BEGIN CERTIFICATE----- and -----END CERTIFICATE-----). These files can store various types of cryptographic information, including X.509 certificates (public keys), private keys (RSA, DSA, ECC), Certificate Signing Requests (CSRs), and certificate chains. Their human-readable, text-based nature makes them easy to inspect and transfer, although the actual cryptographic data within is binary and encoded. They are fundamental for establishing trust and securing communications across the internet, enabling secure communication channels for websites, email, and other network services by providing a standardized way to package and exchange cryptographic material.