# Segments

Segments are a feature of the system that allows you to easily create a list of products that meet specific conditions. Some examples:

* Attribute exists,
* Product completeness,
* The product belongs to a category,
* Product has status

Segments are also used to make a set of products that can be assigned to a specific [API key](../system/settings/api-keys).

{% hint style="info" %}
Segments are dynamic, which means that any changes in the product will be taken into consideration while evaluating segment conditions. That means that if you change anything in the product, segments will be re-evaluated and the products available in them may change automatically. This is done automatically and in the background, so having a lot of segments and lots of products may decrease performance, and you will need to wait a while till segments are recalculated.
{% endhint %}

A list created this way can also be used, for example, to send only some products via API, or be used with a module to [export a file in the .csv format](../data-exchange/ergonode-transfer/exports/creating-a-new-export-job).

