Tapping to pay with your Visa contactless card or payment-enabled mobile/wearable device is a secure way to pay because each transaction generates a transaction-specific, one-time code, that is extremely effective in reducing counterfeit fraud.
To make a payment, your contactless card or payment-enabled mobile/wearable device must be placed within 2 inches of the Contactless Symbol 
located on the checkout terminal in order for the transaction to take place (so you can’t pay accidentally).
You can also rest assured that Visa will protect your payment information from fraud losses and unauthorized purchases with Visa’s Zero Liability Policy*.
See Also
Payment methods in Switzerland