> For the complete documentation index, see [llms.txt](https://docs-29.gitbook.io/usdd-v2/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs-29.gitbook.io/usdd-v2/developers/core-contracts/jug.md).

# Jug

### **Purpose**

Calculates and accrues stability fees on minted USDD. These fees ensure protocol sustainability and discourage excessive borrowing.

### Key Responsibilities

* Accumulate stability fees for particular collateral types .
* Adjusts debt levels to reflect accrued interest.

### Key Methods

* d`rip(ilk)`\
  Performs stability fee collection for a specific collateral type when it is called. Calls `Vat.fold` to update the collateral's rate, total tracked debt, and Vow surplus;

  duty: Annualized stability fee rate.
* `file(what, data) / file(what, ilk, data)`\
  Configures global and per-collateral stability fee rates.
  * Example Parameters:
    * `duty`: Annualized stability fee rate.