But for now, let's check these important **conceptual ideas**. These concepts also apply to any other type of web API. 💡

## Security - HTTPS

In the [previous chapter about HTTPS](https.md){.internal-link target=_blank} we learned about how HTTPS provides encryption for your API.

But even if you never use **FastAPI**, you would benefit from learning a bit about them.

!!! note
    If you are a Python expert, and you already know everything about type hints, skip to the next chapter.

## Motivation

Let's start with a simple example:

```Python
{!../../../docs_src/python_types/tutorial001.py!}
```

Calling this program outputs:

```
John Doe
```

    * A "token" is just a string with some content that we can use later to verify this user.
    * Normally, a token is set to expire after some time.
        * So, the user will have to log in again at some point later.
        * And if the token is stolen, the risk is less. It is not like a permanent key that will work forever (in most of the cases).

It is compatible with:

* PostgreSQL
* MySQL
* SQLite

In this example, we'll use **SQLite**, because it uses a single file and Python has integrated support. So, you can copy this example and run it as is.

Later, for your production application, you might want to use a database server like **PostgreSQL**.

!!! tip

For now, don't pay attention to the rest, only the imports:

```Python hl_lines="3-5"
{!../../../docs_src/nosql_databases/tutorial001.py!}
```

## Define a constant to use as a "document type"

We will use it later as a fixed field `type` in our documents.

This is not required by Couchbase, but is a good practice that will help you afterwards.

```Python hl_lines="9"
{!../../../docs_src/nosql_databases/tutorial001.py!}
```

    {!> ../../../docs_src/body_multiple_params/tutorial004.py!}
    ```

!!! info
    `Body` also has all the same extra validation and metadata parameters as `Query`,`Path` and others you will see later.

## Embed a single body parameter

Let's say you only have a single `item` body parameter from a Pydantic model `Item`.

By default, **FastAPI** will then expect its body directly.

<img src="/img/deployment/https/https03.svg">

The client already **trusts** the entity that generated that TLS certificate (in this case Let's Encrypt, but we'll see about that later), so it can **verify** that the certificate is valid.

Then, using the certificate, the client and the TLS Termination Proxy **decide how to encrypt** the rest of the **TCP communication**. This completes the **TLS Handshake** part.

* 👥 Update FastAPI People. PR [#9999](https://github.com/tiangolo/fastapi/pull/9999) by [@tiangolo](https://github.com/tiangolo).
* 🐳 Update Dockerfile with compatibility versions, to upgrade later. PR [#9998](https://github.com/tiangolo/fastapi/pull/9998) by [@tiangolo](https://github.com/tiangolo).

!!! info
    In this example we use invented custom headers `X-Key` and `X-Token`.

    But in real cases, when implementing security, you would get more benefits from using the integrated [Security utilities (the next chapter)](../security/index.md){.internal-link target=_blank}.

## Dependencies errors and return values

You can use the same dependency *functions* you use normally.

### Dependency requirements

`Query`와 `Path`(나중에 볼 다른 것들도)를 사용하여 문자열 뿐만 아니라 숫자의 제약을 선언할 수 있습니다.

여기서 `ge=1`인 경우, `item_id`는 `1`보다 "크거나(`g`reater) 같은(`e`qual)" 정수형 숫자여야 합니다.

```Python hl_lines="8"
{!../../../docs_src/path_params_numeric_validations/tutorial004.py!}
```

## 숫자 검증: 크거나 같음 및 작거나 같음

동일하게 적용됩니다:

* `gt`: 크거나(`g`reater `t`han)
* `le`: 작거나 같은(`l`ess than or `e`qual)

```Python hl_lines="9"