## OpenAPI: required and nullable fields
In our API specification, you'll see that some response parameters will have a **required** annotation. According to the OpenAPI specification, when a response parameter is marked as **required**, this means that the response key must be returned. However, the value of that response parameter can be `null`.
> 📘 Info
In short, any response parameter marked as required will be returned by our API, but the value can be set to null.