In one sentence: A security key is a small physical device that you plug in or tap to prove it is you when you sign in.
Why it matters: It is one of the strongest second steps, and it helps protect you from fake sites. Some services let you add more than one key. A spare key kept in a safe place helps if you lose the first one.
One thing to do: Open your main email account settings and check whether you can add a security key.
Related terms: passkey, two-factor authentication, phishing
Learn more: The 30-Minute Account Clean-Up; Two-Factor Authentication (2FA): What It Is and How to Turn It On
Checked: 25 Oct 2026. Settings screens change. If yours looks different, search the company's help page.
