Duo Security is a cloud-based identity and access management provider that was founded in 2010 by Dug Song and Jon Oberheide in Ann Arbor, Michigan. The company was acquired by Cisco in 2018 and now operates as part of Cisco Security, serving over 40,000 customers across 100+ countries. Duo provides multi-factor authentication (MFA) and identity security solutions designed to verify user identities and assess device health before granting access to applications, data, and networks. The platform's core capabilities include phishing-resistant MFA, single sign-on (SSO), passwordless authentication, device trust, identity threat detection and response (ITDR), and identity security posture management (ISPM). Additional features include two-factor authentication, remote access controls, and adaptive access policies. The company's solutions support Zero Trust security strategies and are deployed across diverse industries including healthcare, higher education, manufacturing, technology, finance, and public sector organizations. Duo processes over 1.3 billion monthly user authentications globally. The platform integrates with various applications and systems, providing risk-based authentication that adapts to user behavior and context in real time. Duo's approach emphasizes user experience alongside security, aiming to minimize friction while maintaining strong protection against unauthorized access and phishing attacks.