(Apple) Wallet tag is applicable for questions relating to Apple Wallet (formally Passbook), Apple Pay, and Apple's PassKit framework. Wallet makes use of APNS to trigger push updates to pass content.
Apple Wallet (referred to as simply Wallet) is a default application in iOS. Introduced under the name Passbook in iOS6, it was renamed as Wallet in iOS9. Wallet allows users to store coupons, boarding passes, event tickets, store cards and, starting with iOS 8.1, credit cards, loyalty cards, and debit cards for users holding compatible credit cards, in territories where Apple Pay is available.