IT professionals — and increasingly business users, as well — commonly use terms such as event processing, business event management, complex event processing, and various other similar expressions. But confusion about what each represents is rife, in part because an increasing number of business requirements are driving demand for different forms of event processing, even when it is not clear which form to use. Enterprise architects need a taxonomy of both types of events and of the forms that event processing can take. This document provides a concise description of event types and event processing forms so that enterprise architects can guide their enterprise's thinking about how it should approach and deploy event processing.