PKI and SSL, while different, are both certificate-based solutions that establish “trust” with certificates issued by a certificate authority (CA) – whether it’s public trust (SSL) or private trust (PKI). PKI is an entire framework that consists of hardware, software, policies, and more. A PKI also includes a CA, which is what issues the digital certificates to establish trust. Typically that CA is governed internally according to policies and procedures that align with the security and assurance levels required of the organization. SSL is one of the top use cases of PKI. It also involves a CA that issues certificates, but it must be recognized by browsers as a publicly trusted CA. And while there are many use cases for PKI , the purpose of SSL is to secure sensitive data transferred via online communications, like online banking or ecommerce transactions. More on PKI More on SSL