Event processing is a method of tracking and analyzing (processing) streams of information (data) about things that happen (events), and deriving a conclusion from them. Complex event processing, or CEP, consists of a set of concepts and techniques developed in the early 1990s for processing real-time events and extracting information from event streams as they arrive. The goal of complex event processing is to identify meaningful events (such as opportunities or threats) in real-time situations and respond to them as quickly as possible. These events may be happening across the various layers of an organization as sales leads, orders or customer service calls. Or, they may be news items, text messages, social media posts, stock market feeds, traffic reports, weather reports, or other kinds of data. An event may also be defined as a "change of state," when a measurement exceeds a predefined threshold of time, temperature, or other value. Analysts have suggested that CEP will give organizations a new way to analyze patterns in real-time and help the business side communicate better with IT and service departments. CEP has since become an enabling technology in many systems that are used to take immediate action in response to incoming streams of events. Applications are now to be found (2018) in many sectors of business including stock market trading systems, mobile devices, internet operations, fraud detection, the transportation industry, and governmental intelligence gathering. The vast amount of information available about events is sometimes referred to as the event cloud. Conceptual description Among thousands of incoming events, a monitoring system may for instance receive the following three from the same source: church bells ringing. the appearance of a man in a tuxedo with a woman in a flowing white gown. rice flying through the air. From these events the monitoring system may infer a complex event: a wedding. CEP as a technique helps discover complex events by analyzing and correlating other events: the bells, the man and woman in wedding attire and the rice flying through the air. CEP relies on a number of techniques, including: Event-pattern detection Event abstraction Event filtering Event aggregation and transformation Modeling event hierarchies Detecting relationships (such as causality, membership or timing) between events Abstracting event-driven processes Commercial applications of CEP exist in variety of industries and include the detection of credit-card fraud, business activity monitoring, and security monitoring. History The CEP area has roots in discrete