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

# Capture

> Track events with signal.capture()

# Node — Capture

Track events from the server with `signal.capture(options)`. Pass `sessionId` and `windowId` from request headers to correlate with the client session.

## capture(options)

| Option       | Type                       | Required | Description                                              |
| ------------ | -------------------------- | -------- | -------------------------------------------------------- |
| `distinctId` | `string`                   | yes      | User identifier                                          |
| `event`      | `string`                   | yes      | Event name                                               |
| `properties` | `Record<string, JsonType>` | no       | Event properties                                         |
| `timestamp`  | `Date`                     | no       | When the event occurred (default: now)                   |
| `groups`     | `Record<string, string>`   | no       | Groups the user belongs to (e.g. `{ company: 'acme' }`)  |
| `sessionId`  | `string`                   | no       | From `x-signal-session-id` header for client correlation |
| `windowId`   | `string`                   | no       | From `x-signal-window-id` header for client correlation  |

## Example

```typescript theme={null}
const { sessionId, windowId, distinctId } = getSessionInfo(req);

signal.capture({
  distinctId: distinctId || userId,
  event: 'order_created',
  properties: { orderId, amount },
  sessionId,
  windowId,
});
```

Events are queued and sent in batches. All methods are synchronous except [flush](/docs/integrations/node/flush-shutdown) and [shutdown](/docs/integrations/node/flush-shutdown).

## See also

* [Identify](/docs/integrations/node/identify) — Identify users
* [Initialization](/docs/integrations/node/initialization) — getSessionInfo pattern