Apache Storm is a distributed real-time computing system that processes a large volume of high velocity data. Unlike Spark, it does not create micro batches instead, it gives us the ability to process events in real-time mode. Applications where even a delay of seconds can cause a big loss could not go with a near real-time processing engine like Spark. There are a large number of companies that are using Apache Storm for processing events in real time for use cases such as fraud detection, recommendation engines, identifying suspicious activity, and so on.
Apache Storm is a distributed real-time processing engine that provides the ability to process events as quick as they arrive to the node. It is super fast and can process millions of events per machine. Storm is reliable in processing both bounded and unbounded streams of event.