There may scenarios where you want to collect information in a webform that you won't ever need to search or bring into Powerbase. An example could be a question where you ask, "How did you find out about this program?" You may never need to search this information, so it may not be useful to keep in Powerbase. In this case, it may be a better option to create a custom field in the webform itself and keep the response there where you can review it in the webform submission results.
This screen cast will show how to create custom fields in webforms.