# OTP (one-time password)

An OTP is a code valid for a single login or action, usually 4 to 8 digits, sent by SMS, email or generated by an app, that expires after a few minutes.

## What is OTP (one-time password)?

An OTP is a code valid for a single login or action, usually 4 to 8 digits, sent by SMS, email or generated by an app, that expires after a few minutes.

## How OTPs are used

Services send an OTP to confirm that you control a phone number or email, at sign-up and when logging in from a new device. SMS OTPs are the most common because every phone can receive them; app-generated OTPs (TOTP) are more secure because they never travel over the network.

## OTP and temporary numbers

A temporary number receives the SMS OTP in your dashboard instead of your personal phone. The code is the same; only the receiving number changes.

Source: https://smsnitro.com/glossary/otp