unleash.unleash/website/docs/reference/segments.mdx

---
title: Segments
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:::info Availability

Segments are available to Unleash Pro and Unleash Enterprise users since **Unleash 4.13**.

:::

A **segment** is a reusable collection of [strategy constraints](../advanced/strategy-constraints.md).
Like with strategy constraints, you apply segments to [feature toggle activation strategies](../user_guide/activation-strategies.md).

You can apply the same segment to multiple activation strategies.
If you update the segment, the changes will affect every strategy that uses that segment.

Segments let you create user groups based on data available in the Unleash context.
These groups can be as simple or as complex as you want to make them.
You could, for example, use segments to target:
- Users in a specific region
- Users on a specific device type
- Users who signed up before a specific point in time
or any combination thereof.

Because segments stay in sync across strategies, any changes will propagate to all the activation strategies that use them. This also makes them ideal for use cases such as activating or deactivating multiple feature toggles at the same time. In other words, you can use segments to
- release one or more new features at a specified time
- create events with start and end times and guarantee that features will only be active during that period

## Structure and evaluation

Segments are collections of strategy constraints. To satisfy a segment, *all* the constraints in the collection must be satisfied.

If an activation strategy has a segment *and* additional constraints applied, the segment *and* the strategies must all be satisfied. Similarly, if an activation strategy has multiple segments, then they must *must all be satisfied*.

## Creating, updating, and deleting segments

Segments can be created, edited, and deleted from the segments page in the admin UI or via the API (see the [segments API documentation](../api/admin/segments.mdx)).

A segment that is in use **cannot** be deleted. If you'd like to delete a segment that is in use, you must first remove the segment from all the activation strategies that are currently using it.

![The Segments page, listing two existing segments: "Mobile users" and "Users in the APAC region". The navigation menu with the Segments page link is opened and highlighted to provide navigation help.](/img/segments-page.png)