# Versioning

When backwards-incompatible changes are made to the API, a new, dated version is released. A change is considered backwards-incompatible when under the following conditions:

* Resources or fields are removed from responses
* The meaning (`Type`) of an attribute changes

Note that the version of an API does not increase when new resources are added or when new fields are added to a resource. Read our API upgrades guide to see our [API changelog](broken://spaces/RnLJYNhGbpDCQOrCFmiI/pages/OF6XRIr0fLuXmIIqWC50) and to learn more about backwards compatibility.

All requests use your [account API settings](https://app.impact.com/secure/advertiser/accountSettings/techintegration/adv-wsapi-flow.ihtml), unless you override the API version. The changelog lists every available version.

To set the API version on a specific request, you can add the `Ir-Version` querystring parameter or `IR-Version` header.

You can visit your [account API settings](https://app.impact.com/secure/advertiser/accountSettings/techintegration/adv-wsapi-flow.ihtml) to upgrade your API version. As a precaution, use API versioning to test a new API version before committing to an upgrade.

#### Versioning Examples

{% tabs %}
{% tab title="cURL" %}

```bash
curl 'https://api.impact.com/Agencies/<AccountSID>/CompanyInformation' \
	-d 'Ir-Version=2' \
	-G
```

{% endtab %}
{% endtabs %}


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```

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