}
            }
        },
        "components": {
            "securitySchemes": {
                "OAuth2AuthorizationCodeBearer": {
                    "type": "oauth2",
                    "flows": {
                        "authorizationCode": {
                            "authorizationUrl": "authorize",
                            "tokenUrl": "token",
                            "scopes": {},

                }
            }
        },
        "components": {
            "securitySchemes": {
                "OAuth2PasswordBearer": {
                    "type": "oauth2",
                    "flows": {"password": {"scopes": {}, "tokenUrl": "/token"}},
                }
            }
        },

from fastapi.security import OAuth2, OAuth2PasswordRequestFormStrict
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

reusable_oauth2 = OAuth2(
    flows={
        "password": {
            "tokenUrl": "token",
            "scopes": {"read:users": "Read the users", "write:users": "Create users"},
        }
    }
)


class User(BaseModel):
    username: str

from fastapi.security import OAuth2, OAuth2PasswordRequestFormStrict
from fastapi.testclient import TestClient
from pydantic import BaseModel

app = FastAPI()

reusable_oauth2 = OAuth2(
    flows={
        "password": {
            "tokenUrl": "token",
            "scopes": {"read:users": "Read the users", "write:users": "Create users"},
        }
    },
    description="OAuth2 security scheme",

                }
            }
        },
        "components": {
            "securitySchemes": {
                "OAuth2AuthorizationCodeBearer": {
                    "type": "oauth2",
                    "flows": {
                        "authorizationCode": {
                            "authorizationUrl": "authorize",
                            "tokenUrl": "token",
                            "scopes": {},

                }
            }
        },
        "components": {
            "securitySchemes": {
                "OAuth2PasswordBearer": {
                    "type": "oauth2",
                    "flows": {"password": {"scopes": {}, "tokenUrl": "token"}},
                }
            }
        },

It can be used by third party applications and systems.

And it can also be used by yourself, to debug, check and test the same application.

## The `password` flow

Now let's go back a bit and understand what is all that.

The `password` "flow" is one of the ways ("flows") defined in OAuth2, to handle security and authentication.

OAuth2 was designed so that the backend or API could be independent of the server that authenticates the user.

The most common is the implicit flow.

The most secure is the code flow, but is more complex to implement as it requires more steps. As it is more complex, many providers end up suggesting the implicit flow.

!!! note
    It's common that each authentication provider names their flows in a different way, to make it part of their brand.

Am häufigsten ist der „Implicit“-Flow.

Am sichersten ist der „Code“-Flow, die Implementierung ist jedoch komplexer, da mehr Schritte erforderlich sind. Da er komplexer ist, schlagen viele Anbieter letztendlich den „Implicit“-Flow vor.

!!! note "Hinweis"
    Es ist üblich, dass jeder Authentifizierungsanbieter seine Flows anders benennt, um sie zu einem Teil seiner Marke zu machen.

                    },
                },
            },
            "securitySchemes": {
                "OAuth2PasswordBearer": {
                    "type": "oauth2",
                    "flows": {
                        "password": {
                            "scopes": {
                                "me": "Read information about the current user.",
                                "items": "Read items.",