X.509 certificates are most commonly associated with Public Key Infrastructure (PKI). These certificates are used for a variety of security functions, including digital signatures, encryption, and authentication.
PKI: X.509 certificates are a fundamental component of PKI, used to manage encryption keys and authenticate users and devices.
Digital Certificates: They are used to establish secure communications over networks, such as SSL/TLS for websites and secure email communication.
Authentication and Encryption: X.509 certificates provide the means to securely exchange keys and verify identities in various applications, ensuring data integrity and confidentiality.