HOTP
HMAC-based One-Time Password increments a counter each time a code is generated, so the code stays valid until consumed. It is largely superseded by TOTP, which uses time instead and expires on its own. See OTP vs TOTP
HMAC-based One-Time Password increments a counter each time a code is generated, so the code stays valid until consumed. It is largely superseded by TOTP, which uses time instead and expires on its own. See OTP vs TOTP