# NFC

> Very short-range wireless that works with a tap: contactless cards, phones, transit.

- Level: Basic
- Topics: Networks
- URL: https://tidbit.legios.com.ar/nfc/
- In Spanish: [NFC](https://tidbit.legios.com.ar/es/nfc/)

**NFC** (near-field communication) is a wireless technology that only works over a few centimeters, roughly the distance of a tap. It is what happens when you pay by holding a card or a phone against a terminal, go through a subway gate with a transit card, or open a door with a badge. Two devices come close, exchange a small amount of data, and that is it.

One side can be a **tag** with no battery at all: a tiny chip and an antenna inside a card, a sticker or a key fob. The reader's own radio field powers the tag for an instant, just long enough for it to answer. Phones can act as a reader, as a tag, or both, which lets them pay, read a label on a museum display or start pairing with headphones just by touching them.

The very short range is a feature, not a limitation. Because you have to bring the device almost into contact, it is hard to trigger a payment by accident, and someone across the room cannot easily listen in. Cards and phone wallets add their own protections on top: phones usually ask you to unlock them or confirm with your face or fingerprint, and each payment uses a one-time code instead of your real card number. NFC is slow and carries little data, so it is used to start things, not to move files.

## An analogy

A handshake instead of a phone call. It only happens when you are close enough to touch, it is over in a second, and it is enough to say "it's me, go ahead".

## Keep in mind

- Works only within a few centimeters, about the distance of a tap.
- Tags in cards and stickers need no battery; the reader powers them.
- Used for contactless payments, transit cards, badges and quick pairing.
- The tiny range makes accidental or remote triggering hard.

## Go deeper

- [NFC technology (NFC Forum)](https://nfc-forum.org/learn/nfc-technology/)
- [Near-field communication on Wikipedia](https://en.wikipedia.org/wiki/Near-field_communication)

## Related terms

- [Command line](https://tidbit.legios.com.ar/command-line/): Controlling a computer by typing text commands instead of clicking icons.
- [Chip](https://tidbit.legios.com.ar/semiconductor-chip/): A sliver of silicon carrying billions of tiny switches that compute and remember.