Several record types in NFC interactor allow adding an ‘Id’. The record ID is not used / visible when you tap the tag with your phone – therefore, you would usually not need to add the ID to a record.
Therefore, the record ID is hidden by default in the composer. If you need to specify the record ID, you can activate it in the app settings.
IDs can be read by 3rd party apps, and can therefore be helpful for developers in some cases. E.g., a developer can add the ID to a record to add some ‘hidden’ information to a URL tag, which shouldn’t be visible in the URL itself. If the user taps the tag with his phone and the app is not running, the phone would only open the URL. If the tag is tapped while the app is running, it could also retrieve the record ID and therefore for example identify the specific tag.