The term "update field" refers to a type of step that can be incorporated into your automation (a.k.a. drip campaign).
The update field step is unique as it allows you to change a contact record based on behavior in the automation. Update Field will add a value to a contact’s demographics or add them to a category defined in the step.
Drag the Update Field step over to the desired section of your workflow. Click the pencil to set your update specifications:
In the example seen above, we update the Rewards Level contact field if a contact clicks to share the campaign to Twitter. We could have also placed them into a new or existing category.