If you see ‘itunes.com/bill‘ or an unfamiliar charge on your bank, credit card, or debit statement - https://support.apple.com/HT201382 - "Before you contact Apple to request a refund for a charge you don't recognize…"
iTunes Store & Mac App Store: About payment card authorization holds - https://support.apple.com/HT201292 ~$1 to verify card, later removed.