Event Properties are individual pieces of data that an event holds. Think of them as the details that make an event unique. Event properties vary based on the event.
For example, purchase events contain event properties that make up the details of the purchase such as product name, price, sku, and source, while form submission events contain event properties such as the name of the form.
Use Event Properties in Workflows and Rules to dynamically set values for the following actions:
Apply a tag to a person's profile
Set a primary or custom field value on a person's profile
Send an email to a person
Send an internal notification
To learn how to dynamically set custom values and apply tags with event properties, check out how to call event properties with liquid.