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GlossaryTags & Identification

What is a UID?

UID stands for Unique Identifier. Also known as: NFC UID, serial number, unique identifier.

Definition

A UID is the factory-assigned serial number of an NFC or HF RFID chip — typically 7 bytes on common NFC tags — used to identify the tag.

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In HF and NFC tags, the UID is the chip's serial number, written by the manufacturer. Many common NFC chips (such as the NTAG family) use a 7-byte UID, shown as 14 hexadecimal characters. It is the first thing a phone learns when it taps a tag.

Why it matters

Because it is assigned at the factory and cannot normally be changed, the UID gives each tag a stable identity without any encoding step: link the UID to an asset once and every future tap resolves to that asset. It is the HF/NFC counterpart of the UHF TID.

In Asetavo

When you link an NFC tag to an asset in the Asetavo mobile app, the tag's identifier is stored against that asset, so a later tap opens the right record.

In practice

Want to understand this in practice?

GuideRFID vs NFC vs QR codes: which tag should you use?Read method, range, bulk reading and cost compared — so you match each asset to the right tag.Read the guide →
Related features
NFC taggingMobile app
Related terms
NFCNFC (near field communication) is short-range 13.56 MHz RFID that most smartphones can read — tap a phone on a tag to identify an asset.HF RFIDHF RFID operates at 13.56 MHz with short read ranges — centimeters up to about a meter. NFC is a subset of HF RFID.TIDThe TID (tag identifier) is the factory-set, read-only identity of an RFID chip — used to tell genuine tags from cloned ones.EPCThe EPC (Electronic Product Code) is the writable identifier stored in a UHF RFID tag’s EPC memory — the ID a reader reports first.
From definition to done

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