NDEF is a standardized data format specification by the NFC Forum which is used to describe how contextualized data is encoded onto a NFC tag or to be exchanged between two active NFC devices. The vast majority of NFC enabled devices (readers, phones, tablets…) support reading NDEF messages from NFC tags. All NDEF record types can be encoded onto all NFC chip types once they have been NDEF formatted. When choosing an NFC chip type, it is important to consider the maximum size of NDEF data that will need to be stored on the NTAG chip.
NDEF is structures as an NDEF message with at least one NDEF record. Each NDEF record is of a specified record type. At a basic level, an NDEF record contains two components:
- A record type used to contextualize the payload data
- Payload data
Example of an NDEF Message with a Single NDEF Text Record
NDEF describes how contextualized data is stored on an NFC tag; not what happens when a device interacts with an NFC tag. The action that is performed is on the device is determined by the system and applications that are running on the device. Android, iOS and Windows all have different behaviors, with some not having any default behavior for certain record types. An NDEF message can store multiple NDEF records, although the behavior is often different.
There are a handful of record types defined by the NDEF specs: