PKI technologies, in the form of certificates, are ubiquitous. They can be found in email signing and encryption, VPN authorization and access, instant messengers, and other applications that touch users every day. Every time a user opens up an HTTPS connection on the internet, they’re making use of PKI. If your corporate remote email client is using SSL, you’re making use of PKI. Providing some level of trust that users and devices are who they say they are is implicit in all these connection types. This means that PKI, to an extent, is part of your enterprise — even without the explicit configuration of your own PKI, or even understanding anything about how it works.
PKI may also be integrated directly into your network operating system. In Windows Server, PKI is known as Active Directory Certificate Services, and is tightly integrated with the Active Directory service. It has been enhanced with each release of Windows Server, and will likely already have migrated to the most current standard, assuming your network has upgraded to Windows Server 2012 R2.