## Dependencies

FastAPI depends on Pydantic and Starlette.

### `standard` Dependencies

When you install FastAPI with `pip install "fastapi[standard]"` it comes with the `standard` group of optional dependencies:

Used by Pydantic:

* <a href="https://github.com/JoshData/python-email-validator" target="_blank"><code>email-validator</code></a> - for email validation.

Used by Starlette:

        if match != Match.NONE:
            child_scope["route"] = self
        return match, child_scope


class APIRouter(routing.Router):
    """
    `APIRouter` class, used to group *path operations*, for example to structure
    an app in multiple files. It would then be included in the `FastAPI` app, or
    in another `APIRouter` (ultimately included in the app).

    Read more about it in the