YubiKey is a hardware security key that provides authentication for computers, networks, and online services. The device supports multiple authentication protocols including FIDO2/WebAuthn, U2F, Smart card, OpenPGP, and OTP. The product line includes several series: - YubiKey 5 Series offers multi-protocol support with USB-A, USB-C, Lightning, and NFC connectivity options - YubiKey 5 FIPS Series provides FIPS-certified keys meeting NIST SP800-63B AAL3 guidelines for government and regulated industries - YubiKey Bio Series incorporates fingerprint biometric authentication for passwordless logins - Security Key Series delivers FIDO-only authentication keys for consumers and enterprises The keys work with Windows and Mac login, as well as various online services. Authentication is performed through physical touch or tap of the device. YubiKey stores credentials directly on the hardware rather than on mobile devices or computers. Additional products include YubiHSM 2, a hardware security module for cryptographic key protection on servers and applications. The company offers YubiKey as a Service for enterprise deployment and provides software tools including Yubico Authenticator and computer login tools for integration and configuration.