Time-based one-time password (TOTP) is a computer algorithm that generates a one-time password (OTP) using the current time as a source of uniqueness. As an extension of the HMAC-based one-time password algorithm (HOTP), it has been adopted as Internet Engineering Task Force (IETF) standard RFC 6238.[1]
TOTP is the cornerstone of Initiative for Open Authentication (OATH), and is used in a number of two-factor authentication[1] (2FA) systems.