### `HTMLResponse` { #htmlresponse }

Takes some text or bytes and returns an HTML response, as you read above.

### `PlainTextResponse` { #plaintextresponse }

Takes some text or bytes and returns a plain text response.

{* ../../docs_src/custom_response/tutorial005_py310.py hl[2,7,9] *}

### `JSONResponse` { #jsonresponse }

Takes some data and returns an `application/json` encoded response.

And that function takes parameters in the same way that *path operation functions* do.

/// tip

You'll see what other "things", apart from functions, can be used as dependencies in the next chapter.

///

Whenever a new request arrives, **FastAPI** will take care of:

* Calling your dependency ("dependable") function with the correct parameters.

      if (iterations >= maxIterations) {
        @SuppressWarnings("nullness") // safe because we pass sort() a range that contains real Ts
        T[] castBuffer = (T[]) buffer;
        // We've already taken O(k log k), let's make sure we don't take longer than O(k log k).
        sort(castBuffer, left, right + 1, comparator);
        break;
      }
    }
    bufferSize = k;

* It takes each **request** that comes to your application.
* It can then do something to that **request** or run any needed code.
* Then it passes the **request** to be processed by the rest of the application (by some *path operation*).
* It then takes the **response** generated by the application (by some *path operation*).

   * // returns {"foo", "quux"}
   * }
   *
   * <p>This {@code Collector} uses O(k) memory and takes expected time O(n) (worst-case O(n log
   * k)), as opposed to e.g. {@code Stream.sorted(comparator).limit(k)}, which currently takes O(n
   * log n) time and O(n) space.
   *
   * @throws IllegalArgumentException if {@code k < 0}
   * @since 33.2.0 (available since 22.0 in guava-jre)

   *       maxPermits is equal to warmupPeriod.
   *   <li>When _used_, the time it takes, as explained in the introductory class note, is equal to
   *       the integral of our function, between X permits and X-K permits, assuming we want to
   *       spend K saved permits.
   * </ol>
   *

```python
from fastapi import Request
```

/// tip

When you want to define dependencies that should be compatible with both HTTP and WebSockets, you can define a parameter that takes an `HTTPConnection` instead of a `Request` or a `WebSocket`.

///

      if (iterations >= maxIterations) {
        @SuppressWarnings("nullness") // safe because we pass sort() a range that contains real Ts
        T[] castBuffer = (T[]) buffer;
        // We've already taken O(k log k), let's make sure we don't take longer than O(k log k).
        sort(castBuffer, left, right + 1, comparator);
        break;
      }
    }
    bufferSize = k;

# Dependencies - `Depends()` and `Security()`

## `Depends()`

Dependencies are handled mainly with the special function `Depends()` that takes a callable.

Here is the reference for it and its parameters.

You can import it directly from `fastapi`:

```python
from fastapi import Depends
```

::: fastapi.Depends

## `Security()`

# `HTTPConnection` class

When you want to define dependencies that should be compatible with both HTTP and WebSockets, you can define a parameter that takes an `HTTPConnection` instead of a `Request` or a `WebSocket`.

You can import it from `fastapi.requests`:

```python
from fastapi.requests import HTTPConnection
```