Finalized Submissions
API v2.x
When working with the API for form integrations, there's one concept you should know about: finalization. With external POST forms, submissions are immediately visible in the Form Tools interface after the user submits the form. But with the API, it's a little more subtle. Say you have a multi-page form - you might only want those submissions to appear in the Form Tools interface after the user has completed all steps of the form. And what about people that started filling in a form but never completed it? In those cases, you probably wouldn't want to see the submission ever.
To let you control the visibility of these submissions in the Form Tools interface, when using the API you need to explicitly finalize the submissions. This is generally done on the final step of your form. You'll read more about finalization in the processFormSubmission() function and deleteUnfinalizedSubmissions() class methods. For now, it's enough that you understand the idea!