---
title: "Segmentation engine"
slug: "segmentation-engine"
abstract: "An overview of the segmentation engine."
---
# Segmentation engine

The segmentation engine is responsible for building a query from an `ISegmentDefinition` or an `IContactSearchQueryFactory` and returning a list of contacts or a count of contacts that match those criteria:

![segmentation-engine1.png](https://doc.sitecore.com/api/markdown-image/xp/en/developers/105/sitecore-experience-platform/images/segmentation-engine1.png)

The segmentation is an internal component of [core Sitecore roles](https://doc.sitecore.com/xp/en/developers/104/platform-administration-and-architecture/en/scaling-and-configuring-core-roles.html), and is used by the [Content Management](https://doc.sitecore.com/xp/en/developers/104/platform-administration-and-architecture/en/content-management--cm-.html), and [xDB Processing](https://doc.sitecore.com/xp/en/developers/104/platform-administration-and-architecture/en/xdb-processing.html) roles.