---
title: Segments
---

:::info Availability
Segments are an **experimental feature** available to some Unleash Pro and Unleash Enterprise users. [Get in touch](https://slack.unleash.run) if you'd like to help us develop this feature.
:::

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.


## 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.

## 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.

[image of the segments page and the segments item in the menu?]

## When to use segments

Segments let you create user groups based on data available in the Unleash context.
These groups can be as simple or 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.

If you need to keep time-based feature availability in sync across, you can use segments to achieve this too. For instance, you could create a "Black Friday" segment which is only satisfied on that specific Friday and use that to synchronize the availability of a number of related features.
