# Coupon codes promotion rules

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

Coupon code promotions rules are used to link a promotion to a specific [coupon](/core-api-reference/coupons.md) 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 %}


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