Hi Mary, this is a great question and something many Airtable users have asked about.
In addition to the solution listed by Hannah, I recommend checking our Pro Backup for Airtable. It allows you to back up your bases, including all records, field configurations, files & comments and restore each of these data types back to your Airtable account. Unfortunately this app does not back up your interfaces yet, but we will add this option as soon as the public API of Airtable has been updated.