cookies and headers), and will put them in the final response that contains the value you returned, filtered by any `response_model`.

You can also declare the `Response` parameter in dependencies, and set the status code in them. But keep in mind that the last one to be set will win....

And as the `Response` can be used frequently to set headers and cookies, **FastAPI** also provides it at `fastapi.Response`.

///

## Custom Headers

Keep in mind that custom proprietary headers can be added <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">using the 'X-' prefix</a>.

/// tip

Prefer to use the `Annotated` version if possible.

///

```Python hl_lines="7"
{!> ../../docs_src/path_params_numeric_validations/tutorial002.py!}
```

////

But keep in mind that if you use `Annotated`, you won't have this problem, it won't matter as you're not using the function parameter default values for `Query()` or `Path()`.

//// tab | Python 3.9+

```Python hl_lines="10"

## Server Machine and Server Program

There's a small detail about names to keep in mind. 💡

The word "**server**" is commonly used to refer to both the remote/cloud computer (the physical or virtual machine) and also the program that is running on that machine (e.g. Uvicorn).

Just keep in mind that when you read "server" in general, it could refer to one of those two things.

Then set Cookies in it, and then return it:

```Python hl_lines="10-12"
{!../../docs_src/response_cookies/tutorial001.py!}
```

/// tip

Keep in mind that if you return a response directly instead of using the `Response` parameter, FastAPI will return it directly.

```Python
q: str | None = None
```

But the `Query` versions declare it explicitly as being a query parameter.

/// info

Keep in mind that the most important part to make a parameter optional is the part:

```Python
= None
```

or the:

```Python
= Query(default=None)
```

## Check the Docs

You can see the defined cookies in the docs UI at `/docs`:

<div class="screenshot">
<img src="/img/tutorial/cookie-param-models/image01.png">
</div>

/// info

Have in mind that, as **browsers handle cookies** in special ways and behind the scenes, they **don't** easily allow **JavaScript** to touch them.

* You can then further modify the `response` before returning it.

```Python hl_lines="8-9  11  14"
{!../../docs_src/middleware/tutorial001.py!}
```

/// tip

Keep in mind that custom proprietary headers can be added <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">using the 'X-' prefix</a>.

* data validation
* data serialization
* data documentation, etc.

This works the same way as with Pydantic models. And it is actually achieved in the same way underneath, using Pydantic.

/// info

Keep in mind that dataclasses can't do everything Pydantic models can do.

So, you might still need to use Pydantic models.

	FNMADDD	F29, F14, F27		// 7bbbae08
	FNMSUBF	F17, F8, F12		// 8ca1d808
	FNMSUBD	F29, F21, F3		// 63d4ee08

	FMINF	F4, F5, F6		// a6900a01
	FMINF	F4, F5			// a5900a01
	FMIND	F4, F5, F6		// a6100b01
	FMIND	F4, F5			// a5100b01
	FMAXF	F4, F5, F6		// a6900801
	FMAXF	F4, F5			// a5900801
	FMAXD	F4, F5, F6		// a6100901
	FMAXD	F4, F5			// a5100901

	FCOPYSGF	F4, F5, F6	// a6901201