---
title: Audiences
editUrl: https://github.com/Cratis/Chronicle/edit/main/Documentation/events/audiences.mdx
description: Address events to an audience with the audience tag, the [Audience] attribute and ambient audience scopes, and make an audience mandatory for an event type.
lastUpdated: 2026-11-04T00:00:00.000Z
---

An **audience** is the named tag `audience`. It says who an event is addressed to, and it is what a [subscription tag filter](/chronicle/subscriptions/filtering-by-tags/) matches on. The name is available as `WellKnownTags.Audience`.

## Stamping the audience from a property

Mark a property of the event with `[Audience]`. Its value, or the underlying value of a concept, becomes the `audience` tag.

**C#**

```csharp
using Cratis.Chronicle;
using Cratis.Chronicle.Events;

[EventType]
[Public]
public record AudiencesInvitationIssued([property: Audience] string Lobby, string Email);
```

[View C# snippet source on GitHub](https://github.com/Cratis/Chronicle/blob/main/Documentation/client-snippets/events/audiences/audience-property.md)

## Stamping the audience from the surroundings

`EventTags.Audience(value)` opens an ambient scope; events appended inside it are addressed to that audience. Open it twice (nested) to address two audiences. The ambient audience is only stamped on events appended to the **outbox**, or on events whose type is marked `[Audience]`, so it never leaks onto ordinary event log events.

## Requiring an audience

Mark the event *type* with `[Audience]` to make an audience mandatory. Appending it without an `audience` tag, from whatever source, fails with `MissingAudience`. In a unit of work the failure happens when the event is added, not at commit.

**C#**

```csharp
using Cratis.Chronicle;
using Cratis.Chronicle.Events;

[EventType]
[Public]
[Audience]
public record AudiencesRegistrationCompleted(string Organization);

public static class AudiencesRequired
{
    public static async Task Complete(IEventStore eventStore)
    {
        var outbox = eventStore.GetEventSequence(Cratis.Chronicle.EventSequences.EventSequenceId.Outbox);

        // Throws MissingAudience: the event type requires an audience and none was provided.
        // await outbox.Append("org-1", new AudiencesRegistrationCompleted("Acme"));

        using var scope = EventTags.Audience("lobby-a");
        await outbox.Append("org-1", new AudiencesRegistrationCompleted("Acme"));
    }
}
```

[View C# snippet source on GitHub](https://github.com/Cratis/Chronicle/blob/main/Documentation/client-snippets/events/audiences/required-audience.md)

Without the attribute on the type, an audience is optional; nothing in Chronicle forces events to have one.