What is the purpose of the Set Values element, and give an example where it is essential.

Set Values writes into the data JSON without presenting anything to the user, which makes it the connective tissue between elements that were not designed to talk to each other.

1. It assigns one or more node values from constants, merge fields, or formula expressions at the point in the script where it is placed.
2. Reshaping for a downstream action: a Data Mapper Load expects a particular node structure; Set Values builds that structure from values the user entered under different names, so you avoid rewriting the Data Mapper for each consumer.
3. Deriving a value: concatenating first and last name, defaulting a country, or stamping a channel identifier that the business wants recorded but the user should never see or change.
4. Resetting state: when a user goes back and changes a branching answer, a Set Values element can clear now-irrelevant nodes so stale data from the abandoned branch is not saved.
5. The discipline worth mentioning: Set Values is easy to overuse. A script with a dozen of them scattered through the Steps becomes hard to reason about. If you are reshaping heavily, that is a signal the reshaping belongs in a Data Mapper Transform or an Integration Procedure.