OATH (Initiative for Open Authentication) is a global, vendor-neutral organization focused on defining and promoting open standards for strong authentication. It publishes royalty-free specifications for one-time password (OTP) mechanisms and related authentication protocols, including: - HOTP (RFC 4226): HMAC-based One-Time Password algorithm, counter-based, used in hardware tokens and software authenticators. - TOTP (RFC 6238): Time-based One-Time Password algorithm, time-synchronized, used in authenticator apps and online services. - OCRA (RFC 6287): OATH Challenge-Response Algorithm, a flexible framework for challenge/response authentication and transaction signing. OATH's work addresses authentication across cloud, on-premises, and hybrid environments, with a focus on interoperability between tokens, authenticators, and validation servers. The organization provides reference architectures, certification profiles for interoperability validation, and best-practice guides for enterprises migrating from passwords and proprietary OTP systems. OATH also provides guidance for bridging legacy OTP deployments with modern passwordless and multi-factor authentication approaches, and supports technical working groups for implementers to contribute requirements and deployment experience back to the community.