Any number of contact or contactless chip devices that serve cryptographic or authentication functions. They normally depend upon some daemon for interaction with the computer and have dependencies like *PCSC-Lite*.
Smartcards are increasingly being used for more secure Authentication or for PKCS#11 and OpenPGP cryptography (to use with full-disk-encryption FDE or encrypted emails, etc.) Within a unix/linux environment, smartcards are frequently used with applications such as GnuPG (GPG) or Device Mapper LUKS (DM-Crypt) file systems.
A few common smartcards include:
While other devices may also technically be smartcards, they most likely deserve separate tags or are outside of the scope of unix/linux forum (such as mobile phone SIM cards or banking chip (EMV) cards).