This chapter is intended as an introduction to biometric standards, and as a survey of the major efforts in the field. Published consensus standards in a wide range of fields have existed for many years. Biometric standards, however, have been developed recently only as biometric technologies have matured to offer a reliable additional factor for personal authentication, and crucially, as large-scale deployment involving multiple organizations and suppliers has been considered. In virtually all cases, standards are developed in response to a need for interoperability. This creates a foundation for a marketplace of off-the-shelf products, and is a necessary condition to achieve supplier independence, and to avoid vendor lock-in. Interoperability allows modular integration of products without compromising architectural scope, and it facilitates the upgrade process and thereby ameliorates obsolescence.