In one sentence: An SMS code is a short number that a service sends to your phone by text message (SMS), so you can type it to prove it is you.
Why it matters: A text code is better than a password alone. It is one of the weaker second steps, because criminals can sometimes take over a phone number. Never read a code out to anyone who contacts you.
One thing to do: If a service offers a passkey or an authenticator app, add it first. Remove the text code only after the new one works and your recovery codes are saved.
Related terms: SIM swapping, authenticator app, two-factor authentication
Learn more: Why Text-Message Codes Are the Weakest 2FA (and What to Use Instead); SIM Swapping: What It Is and How to Protect Your Phone Number
Checked: 25 Oct 2026. Settings screens change. If yours looks different, search the company's help page.
