Explanation:
Public Key Infrastructure (PKI) is a framework that enables secure communication over networks by managing the creation, distribution, and verification of digital certificates and public keys. It forms the foundation for many secure internet protocols, such as HTTPS and digital signatures.

PKI involves components such as Certificate Authorities (CAs), Registration Authorities (RAs), digital certificates, and cryptographic key pairs. CAs issue digital certificates, which authenticate the identity of users or systems and bind them to their public keys.

PKI enhances cybersecurity by ensuring data confidentiality, integrity, and authenticity. It is widely used for secure email communication, virtual private networks (VPNs), and secure financial transactions.

Additional Information:
PKI plays a critical role in enabling secure e-commerce by allowing websites to present digital certificates that prove their authenticity to users.

Certificate revocation lists (CRLs) and Online Certificate Status Protocol (OCSP) are mechanisms used to revoke and check the status of digital certificates. Without proper PKI management, systems are vulnerable to security breaches.

Formal Definition:
Public Key Infrastructure (PKI) is a framework that manages the creation, distribution, storage, and verification of digital certificates and cryptographic keys to enable secure communication and authentication.