Explanation:

Generally speaking, data analytics comes in four types:
* Descriptive, to answer the question: What's happening?
* Diagnostic, to answer the question: Why's happening?
* Predictive, to answer the question: What will happen?
* Prescriptive, to answer the question: What actions should we take?

Reference:
https://azure.microsoft.com/en-us/blog/answering-whats-happening-whys-happening-and-what-will-happen- with-iot-analytics/