Event storming is a workshop-based method to quickly find out what is happening in the domain of a software program.
The business process is "stormed out" as a series of domain events which are denoted as orange stickies.
This includes people who know the questions to ask (typically developers) and those who know the answers (domain experts, product owners).
The concepts gathered during an event storming session fall into several categories, each with its own colour of sticky note: These are examples, these would be different for different organizations.
Domain events Actors Commands Aggregates External systems Views Errors