---
title: "trace_id"
url: https://develop.sentry.dev/sdk/foundations/transport/event-payloads/properties/trace_id/
---

# undefined

* `trace_id`:

  *Required*. Determines which `trace` the Span belongs to. The value should be 16 random bytes encoded as a hex string (32 characters long).

```json
{
  "trace_id": "1e57b752bc6e4544bbaa246cd1d05dee"
}
```