# Event Messages Event Messages are what Aggregates will raise and what the Event Message Handlers will handle. Event Messages will also be stored in whatever storage backend you decide to use. They are used to rebuild the Aggregates as well. So as you can see, Event Messages are a big part of Event Sourcing! Event Messages consist of 1) Metadata and 2) Payload. The Metadata contains information about the event and the aggregate. The payload is the data that is passed in and used to rebuild the aggregates. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.sonsofphp.com/components/event-sourcing/event-messages.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.