An unfamiliar charge doesn't necessarily mean fraud; it could be a forgotten subscription or a charge under a name you don't recognise. Here's how to check:
Look at the transaction details.
Find the charge in the app and check the merchant's name. If it's a recurring charge, it may be a subscription that you signed up for.
Check for a free trial that has been renewed.
If you recently started a free trial, this may be the first charge after it ended. To stop future charges, log in to the merchant's account and remove your card before the next billing date.
Check whether anyone else has used your card. If you have shared your card details with family or friends, check whether one of them made the charge.
Contact the merchant.
If you recognise the merchant but the charge still seems incorrect, contact them directly to ask about it and request a refund if necessary.
If it's unauthorised
If you've ruled out the above and still don't recognise the charge, your card may have been used without your permission.
Follow the steps in What should I do if my card is charged fraudulently? right away to protect your account.