Automatically prepopulate any field so that a user does not need to type in the values themselves. This features requires use of the Expression Builder to find, manipulate, and format the data to be used for the default value. Setting a default value does NOT save the value. The user must still save the form. The default value applies only the particular instance of the field; it is local not global
Settings
Simple - Build an Expression - You can type a value or build one using the Expression Builder
Advanced - Run Actions - Use this when your default value depends on either context or some other value. For example, let's say you offer a subscription to your application. You would like to send your users a reminder email when the subscription is about to expire. Using the Advanced Default Value, you can set a date field for this reminder to be sent two weeks (or any other amount of time) before the subscription end date.