Public-Key Infrastructure (PKI) is a cybersecurity framework that uses encryption methods to secure communication and ensure the authenticity of data transmission. It consists of hardware, software, policies, and standards that work together to manage and distribute digital certificates, which bind cryptographic keys to entities—such as individuals, organizations, or devices—and validate their authenticity through trusted Certificate Authorities (CAs). PKI facilitates a variety of security protocols, including HTTPS, digital signatures, and email encryption, making it essential for secure online transactions and communications.