In one sentence: An authenticator app is an app on your phone that shows a short code, which you type after your password.
Why it matters: The code usually changes every 30 seconds, and the app does not need a phone signal to make it. A thief who learns your password cannot sign in without the code. It is a stronger choice than a code sent by text message.
One thing to do: Add an authenticator app to your main email account, then check that it works.
Related terms: two-factor authentication, SMS code, recovery code
Learn more: Authenticator Apps: What They Are and How to Set One Up
Checked: 25 Oct 2026. Settings screens change. If yours looks different, search the company's help page.
