# Coupon codes promotion rules

Commerce Layer provides a promotional engine built on top of two main resources: [promotions](https://docs.commercelayer.io/core-api-reference/promotions) and [promotion rules](https://docs.commercelayer.io/core-api-reference/promotion_rules).

Coupon code promotions rules are used to link a promotion to a specific [coupon](https://docs.commercelayer.io/core-api-reference/coupons) so that the promotion is triggered only based on the coupon code (if the coupon is not expired).

{% hint style="info" %}
The number of promotions associated with a coupon code promotion rule is **unlimited**.
{% endhint %}