But it's still part of the same **FastAPI** application/web API (it's part of the same "Python Package").

You can create the *path operations* for that module using `APIRouter`.

### Import `APIRouter`

You import it and create an "instance" the same way you would with the class `FastAPI`:

```Python hl_lines="1  3" title="app/routers/users.py"

* There can be **multiple processes** of the **same program** running at the same time.

If you check out the "task manager" or "system monitor" (or similar tools) in your operating system, you will be able to see many of those processes running.

## Password hashing

"Hashing" means converting some content (a password in this case) into a sequence of bytes (just a string) that looks like gibberish.

Whenever you pass exactly the same content (exactly the same password) you get exactly the same gibberish.

But you cannot convert from the gibberish back to the password.

### Why use password hashing

# Cookie Parameters

You can define Cookie parameters the same way you define `Query` and `Path` parameters.

## Import `Cookie`

First import `Cookie`:

=== "Python 3.10+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/cookie_params/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="3"
    {!> ../../../docs_src/cookie_params/tutorial001_an_py39.py!}
    ```

=== "Python 3.8+"

=== "Python 3.10+"

    You can use the same builtin types as generics (with square brackets and types inside):

    * `list`
    * `tuple`
    * `set`
    * `dict`

    And the same as with Python 3.8, from the `typing` module:

    * `Union`
    * `Optional` (the same as with Python 3.8)
    * ...and others.

# Request Forms and Files

You can define files and form fields at the same time using `File` and `Form`.

!!! info
    To receive uploaded files and/or form data, first install <a href="https://github.com/Kludex/python-multipart" class="external-link" target="_blank">`python-multipart`</a>.

    E.g. `pip install python-multipart`.

## Import `File` and `Form`

=== "Python 3.9+"

    ```Python hl_lines="3"

After that, all of the processing logic is the same.

But because of our changes in `GzipRequest.body`, the request body will be automatically decompressed when it is loaded by **FastAPI** when needed.

## Accessing the request body in an exception handler

!!! tip

### Multiple Applications

In the same server (or servers), there could be **multiple applications**, for example, other API programs or a database.

Only one process can be handling the specific IP and port (the TLS Termination Proxy in our example) but the other applications/processes can be running on the server(s) too, as long as they don't try to use the same **combination of public IP and port**.

    }
}
```

!!! note
    Notice that even though the `item` was declared the same way as before, it is now expected to be inside of the body with a key `item`.


**FastAPI** will do the automatic conversion from the request, so that the parameter `item` receives it's specific content and the same for `user`.

## Conditional OpenAPI from settings and env vars

You can easily use the same Pydantic settings to configure your generated OpenAPI and the docs UIs.

For example:

```Python hl_lines="6  11"
{!../../../docs_src/conditional_openapi/tutorial001.py!}
```

Here we declare the setting `openapi_url` with the same default of `"/openapi.json"`.

And then we use it when creating the `FastAPI` app.