# Order Types

Orders are instructions to buy or sell assets at specified conditions. They define what, when, and how trades should execute on the exchange.

Nexus will support a diverse range of order types and configurations:

* **Market:** Executes immediately against resting liquidity; any unfilled size is canceled.
* **Limit:** Placed at a specific price and stays on the order book until filled or cancelled. Filled at selected limit price or better
  * GTD (Good-Till-Date): Stays live until the chosen expiry or when the order fills.
  * IOC (Immediate-or-Cancel): Fills what it can instantly, cancels the rest.
* **Stop:**
  * Stop Market: A market order that is executed at the best market price when mark price reaches selected market price
  * Stop Limit: A limit order that is only executed at selected limit price after mark price reaches selected trigger price.
* **Market close orders:** Automatically-size to fully close your current position, canceling any resting or untriggered orders before closing automatically.
* **Reduce-only orders:** Ensures the order can only decrease your current open position size.
  * Limit: Limit reduce-only orders automatically adjust if a subsequent order reduces your current position