EventStorming Domain Events, Commands, and Hotspots
A plain-language reference for the main EventStorming card types and how they help teams understand software and business processes.
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Domain event
A domain event is a meaningful fact that already happened. Write it in past tense, such as Payment authorized or Account created. Events form the backbone of an EventStorming timeline.
Command
A command is an intention that may cause an event, such as Submit order or Approve refund. Commands usually come from an actor, another system, or a policy.
Actor
An actor is a person, role, or system that initiates an action. Examples include Customer, Support Agent, Warehouse Worker, or Checkout Service.
Policy
A policy is a business rule or reaction that connects an event to a later action. For example, When payment is authorized, send confirmation.
Read model
A read model is information someone needs to make a decision. Examples include an order summary, available stock view, or delivery status screen.
External system
An external system is outside the process boundary being explored, such as a payment provider, courier, tax service, or identity provider.
Aggregate
An aggregate is a possible consistency boundary discovered during deeper modelling. It should be treated as a hypothesis during the workshop, not as a decision that must be correct immediately.
Hotspot
A hotspot records a question, risk, contradiction, or unresolved disagreement. Hotspots make uncertainty visible and give the team a concrete follow-up list.
Use the EventStorming Board to place these concepts on a shared process timeline.
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