Answer:
RFID (radio frequency identification)
Step-by-step explanation:
Radio Frequency Identification makes use of electromagnetic fields to automatically identify and track tags attached to objects. The tags holds electronically stored information. A RFID tag can be passive, that is, only tracks tags that are very close to it and needs no power, or Active, that is, it needs small battery power and can track tags close to 100 meter way. It does not need a line of sight to track, which makes it better to use in phones and other hand held devices.
With this technology, a shopper can automatically pay for items at checkout points.