Definition
Passkey
A cryptographic login credential tied to your device that replaces passwords entirely, resistant to impersonation scam because there is no secret to type or steal.
A passkey is a key pair generated on your device: the private key never leaves it, and the public key is registered with the service. Logging in proves possession of the device (via biometric or PIN unlock) rather than transmitting a password that could be phished or leaked.
Why it matters: passkeys remove the two biggest password failure modes — reuse and impersonation scam — at the protocol level. Where a service offers one, it is a straightforward upgrade over even a strong password plus 2FA.