And `items.router` contains the `APIRouter` inside of the file `app/routers/items.py`.

With `app.include_router()` we can add each `APIRouter` to the main `FastAPI` application.

It will include all the routes from that router as part of it.

!!! note "Technical Details"
    It will actually internally create a *path operation* for each *path operation* that was declared in the `APIRouter`.