Event Modeling is a way to design a blueprint for an Information System of any size or scale. It is done in a way that allows the clearest communication of the system's workings to the largest possible cross-section of roles in an organization. The system can be checked for completeness by following the single thread of data propagation through it.
To help better understand and model an information system with clarity for all (linking UX/UI all the way through to persistance) through a visual representation.
Check out these great links which can help you dive a little deeper into running the Event Modeling practice with your team, customers or stakeholders.