Publisher Summary This chapter describes the Open Grid Services Architecture (OGSA)—the standards-based Grid computing framework. It introduces the service-oriented architecture principles that underlie OGSA and provides a detailed description of the Web services mechanisms and the Open Grid Services Infrastructure specification that together define the core interfaces and behaviors underlying OGSA. The development of OGSA represents a natural evolution of the Globus Toolkit 2.0 in which the key concepts of factory, registry, reliable and secure invocation, and so on exist in a less general and flexible form and without the benefits of a uniform interface definition language. The development of OGSA also represents a natural evolution of Web services. By integrating support for transient, stateful service instances with existing Web services technologies, OGSA extends significantly the power of the Web services framework, while requiring only minor extensions to existing technologies. A defining feature of Grids is the sharing of networks, computers, and other resources and services. This sharing introduces a need for resource and service management.