Also, HTTP headers are case-insensitive, so, you can declare them with standard Python style (also known as "snake_case").

So, you can use `user_agent` as you normally would in Python code, instead of needing to capitalize the first letters as `User_Agent` or something similar.

If for some reason you need to disable automatic conversion of underscores to hyphens, set the parameter `convert_underscores` of `Header` to `False`:

=== "Python 3.10+"

INFO:     Application startup complete.
```

</div>

<details markdown="1">
<summary>About the command <code>uvicorn main:app --reload</code>...</summary>

The command `uvicorn main:app` refers to:

* `main`: the file `main.py` (the Python "module").
* `app`: the object created inside of `main.py` with the line `app = FastAPI()`.
* `--reload`: make the server restart after code changes. Only do this for development.

But then the attackers try with username `stanleyjobsox` and password `love123`.

And your application code does something like:

```Python

  - author: Abhinav Tripathi - Microsoft Blogs
    link: https://devblogs.microsoft.com/cosmosdb/azure-cosmos-db-python-and-fastapi/
    title: Write a Python data layer with Azure Cosmos DB and FastAPI
  - author: Donny Peeters
    author_link: https://github.com/Donnype
    link: https://bitestreams.com/blog/fastapi-sqlalchemy/
    title: 10 Tips for adding SQLAlchemy to FastAPI
  - author: Jessica Temporal

Next, it 🤖 takes the first task to finish (let's say, our "slow-file" 📝) and continues whatever it had to do with it.

That "wait for something else" normally refers to <abbr title="Input and Output">I/O</abbr> operations that are relatively "slow" (compared to the speed of the processor and the RAM memory), like waiting for:

* the data from the client to be sent through the network

INFO:     Application startup complete.
```

</div>

<details markdown="1">
<summary>About the command <code>uvicorn main:app --reload</code>...</summary>

The command `uvicorn main:app` refers to:

* `main`: the file `main.py` (the Python "module").
* `app`: the object created inside of `main.py` with the line `app = FastAPI()`.
* `--reload`: make the server restart after code changes. Only do this for development.

# CORS (Cross-Origin Resource Sharing)

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">CORS or "Cross-Origin Resource Sharing"</a> refers to the situations when a frontend running in a browser has JavaScript code that communicates with a backend, and the backend is in a different "origin" than the frontend.

## Origin

In contrast to a "**container image**" that is the stored static contents, a "**container**" normally refers to the running instance, the thing that is being **executed**.

=== "Python 3.8+"

    ```Python hl_lines="21"
    {!> ../../../docs_src/path_operation_configuration/tutorial005.py!}
    ```

!!! info
    Notice that `response_description` refers specifically to the response, the `description` refers to the *path operation* in general.

!!! check
    OpenAPI specifies that each *path operation* requires a response description.

You can read more about this in the [Advanced User Guide](../advanced/index.md){.internal-link target=_blank}.

## Details

The first `"/static"` refers to the sub-path this "sub-application" will be "mounted" on. So, any path that starts with `"/static"` will be handled by it.

The `directory="static"` refers to the name of the directory that contains your static files.

The `name="static"` gives it a name that can be used internally by **FastAPI**.