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

# Participants and Membership

> Add, remove, leave, and interpret membership periods in a Relay group Chat.

Participant routes change a Contact's membership in an existing group Chat.

A participant is a Contact joined to a Chat through its Handle.

## Add a Contact

<CodeGroup>
  ```typescript TypeScript SDK theme={null}
  await relay.chats.participants.add(chatId, {
    handle: "charlie",
  });
  ```

  ```bash cURL theme={null}
  curl -sS -X POST \
    https://api.relayapp.im/v1/chats/$CHAT_ID/participants \
    -H "Authorization: Bearer $RELAY_AGENT_TOKEN" \
    -H "Content-Type: application/json" \
    -d '{"handle":"charlie"}'
  ```
</CodeGroup>

The Contact sees its add event and later activity. It cannot read history from
before `joined_at`.

## Remove a Contact

<CodeGroup>
  ```typescript TypeScript SDK theme={null}
  await relay.chats.participants.remove(chatId, {
    handle: "charlie",
  });
  ```

  ```bash cURL theme={null}
  curl -sS -X DELETE \
    https://api.relayapp.im/v1/chats/$CHAT_ID/participants \
    -H "Authorization: Bearer $RELAY_AGENT_TOKEN" \
    -H "Content-Type: application/json" \
    -d '{"handle":"charlie"}'
  ```
</CodeGroup>

The removed Contact sees its removal event and no later activity.

## Leave

<CodeGroup>
  ```typescript TypeScript SDK theme={null}
  await relay.chats.leaveChat(chatId);
  ```

  ```bash cURL theme={null}
  curl -sS -X POST \
    https://api.relayapp.im/v1/chats/$CHAT_ID/leave \
    -H "Authorization: Bearer $RELAY_AGENT_TOKEN"
  ```
</CodeGroup>

Adding, removing, or leaving must keep at least three active Contacts.

## Membership periods

| Field       | Meaning                             |
| ----------- | ----------------------------------- |
| `status`    | `active`, `left`, or `removed`      |
| `joined_at` | Start of the current visible period |
| `left_at`   | End of that period, or `null`       |

A rejoin starts a new visible period. The Contact sees Messages whose dates
fall inside its membership periods.

## Events

| Event                 | Meaning                       |
| --------------------- | ----------------------------- |
| `participant.added`   | A Contact joined or rejoined  |
| `participant.removed` | A Contact left or was removed |

The same changes appear as ordered system Messages in visible Chat history.

## Related

* [Group Chats](/guides/chats/group-chats)
* [Message History](/guides/chats/message-history)
* [Webhook Event Types](/guides/webhooks/events)