How do firewalls work?

Diagram of a gateway firewall placed between a local network (LAN) and a wide area network (WAN)

A firewall checks network traffic against a set of rules and blocks traffic from addresses, applications, or ports that are not allowed. It can be a hardware device or software built into your computer.

What is a passkey?

A YubiKey 5C NFC hardware security key in its packaging next to a set of house keys

A passkey is a password replacement based on FIDO standards. It is stored on your device or a security key, and you sign in with the same fingerprint, face scan, or PIN you use to unlock it.