Personal Identity Verification (PIV) is defined in FIPS 201. It is a US government standard defining various authentication and cryptographic operations using a smart card. It defines a set of functions and specifies behavior of a smart card. To be a PIV-compliant smart card, a device must implement these functions in the specified manner.
A developer that wants to build an application that utilizes a PIV-compliant smart card can read the PIV specification, create the command APDUs (see the article on APDUs), send them over an appropriate transport protocol, and interpret the response APDUs.