OTP, one-time password
An OTP is a short code, valid once and for a few minutes, that a service sends to prove you control a phone number.
In detail
Most are four to eight digits, generated server-side and tied to one signup or login attempt. The code is the cheap half of the transaction; the expensive half is a number the service is still willing to send it to. Reusing one number across several accounts on the same service is the fastest way to get its whole range refused.
Also known as
- one-time password
- one time code
- 2fa code
Related terms
- SMS verificationSMS verification is the check where a service sends a code by text message and only proceeds once you type that code back.
- Code validityCode validity is how long a verification code stays usable after it is sent: a few minutes, set by the service not the carrier.
- Sender IDA sender ID is the name or number an SMS appears to come from: an alphanumeric string, a shortcode, or an ordinary long number.