Public key infrastructure (PKI) is a catch-all term for everything used to establish and manage public key encryption, one of the most common forms of internet encryption. It is baked into every web browser in use today to secure traffic across the public internet, but organizations can also deploy it to secure their internal communications.
The most crucial concept involved in PKI is, as its name implies, the public cryptographic keys that are at its core. These keys not only are part of the encryption process, but they help authenticate the identity of the communicating parties.
Why is PKI important? It’s because this combination of encryption and authentication makes trustworthy online communication possible.
Source:: IT news – Security