What is PKI - Public Key Infrastructure?

Public key infrastructure (PKI) consists of a set of roles, hardware, software, policies, processes and procedures needed to create, manage, distribute, use, store and revoke digital certificates and manage public-key encryption. 

PKI is the foundation for Secure Socket Layer (SSL) and Transport Layer Security (TLS), which protect and authenticate traffic over the internet and represent a system of encryption that authenticates and secures communications between two systems. PKI establishes the trusted business environment for applications, such as digital signatures (e-signatures) and e-commerce, and is increasingly being utilized to secure IoT. Some experts say blockchain could become competitive with PKI.