Public key infrastructure (PKI) is a framework of policies, technologies, and procedures used to create, manage, distribute, store, and revoke digital certificates and public keys. PKI enables secure communication and authentication over networks by using a pair of cryptographic keys: a public key that can be shared openly and a private key that is kept confidential. This infrastructure supports activities such as digital signatures, encryption, and secure email, ensuring the integrity, confidentiality, and authenticity of data. PKI is essential for establishing trust in electronic transactions and communications, enabling secure interactions in various digital environments.