> For the complete documentation index, see [llms.txt](https://docs.xccy.finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.xccy.finance/introduction/readme.md).
# Why Fixed Rates Matter
Crypto has learned how to trade, lend and speculate. What it still hasn't learned is how to **lock a rate**.
Almost every yield on-chain floats. Supply USDC to a lending market and your return moves with utilization — more borrowers, the rate rises, more depositors, it falls. Borrow against collateral and your cost moves the same way, usually in the direction you did not want. None of that is a defect. It is what a utilization curve does. But it means neither side of the market knows today what the next six months will have paid.
That is tolerable while you are farming. It stops being tolerable the moment you have to plan:
* A treasury cannot write a runway against a yield that halves in a week.
* A leveraged borrower cannot size a position against a cost that can double overnight.
* Nobody can compare two venues, or two terms, when neither quotes a number that survives the day.
Traditional markets answered this decades ago with the **interest rate swap**: one party pays a fixed rate, the other pays a floating one, and only the difference between them changes hands. The principal never moves. The whole of fixed income exists to answer one question:
> *"What will my rate be over time?"*
## What XCCY does about it
XCCY puts interest rate swaps on Stellar, over the floating rates that Blend, Alula and XOXNO already pay. Your deposit stays in the lending market and keeps earning that market's rate. The swap trades that rate away for a fixed one, for a term with a fixed end date.
Three things follow from how it is built:
* **The rate is discovered, not announced.** Liquidity providers quote bands of fixed rates and takers hit them. The protocol publishes no curve and holds no view on where rates should be.
* **The book that discovers the rate holds no money.** Every token in the system sits in one contract, which is also the only contract that decides whether an account is solvent.
* **The protocol never takes the other side.** In the rate market your counterparty is another user — the protocol quotes nothing and runs no book against you.
What it does not do is make the position free of consequences. Capital is committed until maturity, the fee is paid up front for the whole term, and an account that falls under its margin threshold can be closed by anyone. Those are on the label — see [What you commit to](/products/commitments-and-risks.md).
The whole Stellar stack is deployed and running on **testnet**, and only there. No Stellar mainnet deployment, no external audit, and a redeploy replaces every address at once.
## Where to go next
| If you want | Read |
| --------------------------------------------- | ----------------------------------------------- |
| The protocol in one page | [What is XCCY](/introduction/what-is-xccy.md) |
| The path from a floating rate to a locked one | [How it works](/introduction/how-it-works.md) |
| A fixed yield on something you already hold | [LockYield](/products/lock-yield.md) |
| A fixed cost on a floating-rate loan | [LockBorrow](/products/lock-borrow.md) |
| To trade or quote the rate itself | [How rates are quoted](/trading/rate-market.md) |
| To know exactly what can go wrong | [How margin works](/risk/risk.md) |
| To build on it | [Contracts](/developers/smart-contracts.md) |
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