EMV QR code
EMVCo's common format for payment QR codes, so that a single code at the till can be read by many banks and wallets.
The specification arrived in 2017 in two flavours. In Merchant-Presented Mode the shop displays a code — often a printout taped to the counter — and the customer scans it with their app. In Consumer-Presented Mode the customer shows a code carrying a one-time token and the till reads it. The payload is a chain of TLV fields: a two-digit ID, a two-digit length, then the value, covering merchant identity, currency, country, an optional amount and finally a CRC checksum.
It became the foundation for a string of national schemes: Brazil's Pix, Thailand's PromptPay, Singapore's SGQR and India's BharatQR. The point is interoperability. Before the standard every wallet had its own code, and a market stall in Asia could end up with five different stickers in the window. Europe's EPC QR is a different and simpler beast that merely pre-fills a SEPA transfer.