NDEF is a lightweight, compact binary format that can contain various data types defined by URL, vCard and NFC.

The NDEF consists of various data records, and each record consists of a header and a payload. The data type and size of the NDEF record are indicated by the header of the payload. The header here contains three parts, namely Length, Type and Identifier.

NFC Data Exchange Format (NDEF) is a standardized data format that can be used to exchange information between any compatible NFC device and another NFC device or label. The data format consists of NDEF messages and NDEF records. This standard is maintained by the NFC forum and can be referenced for free, but it can only be downloaded after accepting the license agreement.

The recommended detection tool for NDEF on iOS side is NFC Master, which can be used to read and write NDEF tags conveniently.

The NDEF format is used to store and exchange information such as URIs, plain text, etc. using commonly understood formats. NFC tags such as Mifare Classic cards can be configured as NDEF tags, and any other NDEF-compatible device can understand and access the data written to them by an NFC device (NDEF record). NDEF messages can also be used to exchange data between two active NFC devices in "peer to peer" mode. By complying with the NDEF data exchange format in the communication process, devices that do not know each other or do not have a common language can share data in an organized and understandable way.