> For the complete documentation index, see [llms.txt](https://docs.syfu.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.syfu.io/glossary/a-d.md).

# 12.1 A–D

This section summarizes key terms essential to understanding SyFu.\
Explanations are simplified so that even beginners won’t get lost.

***

### **A–D**

* **BIND**\
  The act of linking check-in location data with payment data. Required to earn rewards.
* **Bond**\
  One of the NFT parameters. Increases with continued usage and affects reward efficiency.
* **Breed**\
  The mechanism where two Prime-stage NFTs are combined to generate a new NFT.
* **Check-in**\
  The act of registering store visit location data through the app.
* **CIR (Check-in Recovery)**\
  A system that restores the 12-hour check-in cooldown by spending Econ.
* **Common / Uncommon / Rare / Epic**\
  NFT rarity tiers. Higher rarity yields EVT more efficiently.
* **DID (Decentralized ID)**\
  A digital ID tied to the user, recording payment data and NFT activity.