# Free shipping promotions

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).

When triggered, free shipping promotions are responsible for setting to zero the shipping amount of the orders involved.

## Application scope

Free shipping promotions can be optionally defined by currency code or restricted to a specific active market (in the latter case the currency code is inherited by the market's price list). Within the time window given by their activation and expiration dates, free shipping promotions that have not reached their total usage limit are considered active. If no promotion rule is associated with an active free shipping promotion, the discount is applied to:

* All the orders, if the promotion is not restricted to a specific currency or market.
* All the orders in the specified currency, if a currency code is specified but the promotion is not restricted to a specific market.
* All the orders of the market in scope, if the promotion is attached to a market.

Otherwise, if one or more promotion rules are defined, the promotion is triggered only when it matches all of them.

{% hint style="info" %}
Only one free shipping promotion can be applied to an order, as long as you haven't already reached the maximum number of active promotions allowed for your organization.
{% endhint %}

## Discount calculation and distribution

The total discount due to free shipping promotions is calculated and distributed on the line items of type `shipments` only.


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