Passkeys
Passwordless FIDO2/WebAuthn credentials that sync between your devices via iCloud Keychain, Google Password Manager, 1Password, etc. The Apple/Google/MS-pushed replacement for passwords.
"Multi-device FIDO credentials" — the technical term the FIDO Alliance launched in spring 2022. Different from classic hardware passkeys on a YubiKey because the private key is synced (end-to-end encrypted) across the user's devices. Phishing-resistant: the relying-party domain is part of the signature, so you can't be fooled into signing against a fake domain. Cross-device flow via QR + Bluetooth (to log in on a shared computer). Support: Apple since iOS 16, Google since Android 9, Microsoft since Windows 11.