Public Key Infrastructure (PKI) is a framework that enables secure communication and authentication over networks. It uses a combination of hardware, software, policies, and standards to manage digital certificates, which are essential for verifying identities and encrypting data. PKI relies on a pair of cryptographic keys: a public key, which can be shared openly, and a private key, which is kept secret. The primary purpose of PKI is to establish trust in digital transactions. By using digital certificates issued by trusted Certificate Authorities, PKI ensures that users can confidently exchange information without the risk of interception or fraud. This infrastructure is vital for online banking, e-commerce, and secure email communications.