Public Key Infrastructure (PKI) is a comprehensive framework that manages digital certificates and public-key encryption. PKI enables secure electronic transfer of information over networks by authenticating the identity of users, devices, or services. It uses a combination of public and private cryptographic keys to encrypt and decrypt data, ensuring confidentiality, integrity, and non-repudiation. PKI involves components such as Certificate Authorities (CAs), Registration Authorities (RAs), and digital certificates. These elements work together to issue, validate, and revoke certificates, making PKI essential for secure email, web browsing (HTTPS), VPNs, and other encrypted communications. By establishing trust between parties, PKI plays a critical role in modern cybersecurity.