Logic
Logic can be used to calculate something that will be useful later in the form, such as a value based on question answers and standard form variables. You can then use the calculated value in branching rules, branching rules, prefills, and rules to use with action templates.
Prefills
Prefills can be used to populate a specific question in the form with a previous answer. You can also populate questions with dynamic default values, for example, based on standard variables or the value of a Logic.