> ## Documentation Index
> Fetch the complete documentation index at: https://docs.apollodeploy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Segments

> Create static contact groups and use them as explicit audiences

A segment is a named static group of contacts.
Membership changes only when an operator or API caller adds or removes a contact.

<Note>
  Segments do not continuously evaluate property rules.
  If your application needs rule-driven membership, calculate the rule in your system and synchronize the resulting membership deliberately.
</Note>

## Create a segment

Open **Segments**, create a clear name, then add existing contacts.
Use names that explain the business boundary, such as **Cape Town beta customers** or **Security incident contacts**.
Avoid names tied to a one-time date unless the group is intentionally temporary.

## Manage membership

Open a segment to inspect its contacts.
Add an existing contact or remove a current member.
Removing membership does not delete the contact, its properties, or its topic preferences.

## Send to a segment

The Email API accepts one segment ID in `to`.
The ID must be the only recipient and cannot be combined with CC or BCC.
Signal resolves at most 50 recipients for one audience send.
Each resolved recipient receives an independent message record and lifecycle.

Before sending:

* Confirm the membership is current.
* Confirm the communication purpose and topic preference.
* Account for global subscription and suppression state.
* Use test mode for request-path validation, then perform a controlled real send.

## Delete a segment

Deleting the segment removes the grouping.
It does not delete member contacts.
Remove or replace application references to the segment ID before deletion.

<Warning>
  Do not treat segment membership as consent.
  A member can still be unsubscribed, topic-ineligible, or suppressed.
</Warning>

## SDK example

After creating an authenticated client with the matching [SDK setup guide](/signal/send-with/sdk-overview),
use the operation for your language or framework.

<CodeGroup dropdown>
  ```typescript TypeScript theme={"dark"}
  const segments = await signal.segments.listSegments(projectId, {
    headers: { Authorization: `Bearer ${process.env.SIGNAL_API_KEY}` },
  });
  ```

  ```python Python theme={"dark"}
  segments = signal.segments.list_segments(project_id)
  ```

  ```go Go theme={"dark"}
  segments, err := client.Segments.ListSegments(ctx, projectID)
  if err != nil {
      panic(err)
  }
  ```

  ```ruby Ruby theme={"dark"}
  segments = signal.segments.list_segments(project_id: project_id)
  ```

  ```ruby Rails theme={"dark"}
  segments = ApolloDeploySignalSdkRails.rails_client.segments.list_segments(
    project_id: project_id
  )
  ```

  ```php PHP / Laravel theme={"dark"}
  $segments = $signal->segments()->listSegments($projectId);
  ```

  ```java Java theme={"dark"}
  var segments = signal.segments().listSegments(projectId);
  ```

  ```kotlin Kotlin theme={"dark"}
  val segments = signal.segments.listSegments(projectId)
  ```

  ```csharp .NET theme={"dark"}
  var segments = await signal.Segments.ListSegmentsAsync(projectId);
  ```

  ```rust Rust theme={"dark"}
  let segments = signal.segments.list_segments(project_id.to_string()).await?;
  ```

  ```elixir Elixir theme={"dark"}
  {:ok, segments, _metadata} = ApolloSignal.Client.list_segments(client, project_id)
  ```

  ```swift Swift theme={"dark"}
  let segments = try await signal.segments.listSegments(projectId: projectId)
  ```

  ```zig Zig theme={"dark"}
  var api = client.segments();
  var result = try api.listSegments(project_id, .{});
  defer result.deinit();

  switch (result) {
      .success => |_| {},
      .api_error => return error.SignalApiError,
  }
  ```
</CodeGroup>