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"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

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"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

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"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

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"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

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"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

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<div style="text-align: left; direction: ltr;">"I’m over the moon excited about <strong>FastAPI</strong>. It’s so fun!"</div>

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"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

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"_I’m over the moon excited about **FastAPI**. It’s so fun!_"

        * `clientCredentials`
        * `authorizationCode`
    * But there is one specific "flow" that can be perfectly used for handling authentication in the same application directly:
        * `password`: some next chapters will cover examples of this.
* `openIdConnect`: has a way to define how to discover OAuth2 authentication data automatically.
    * This automatic discovery is what is defined in the OpenID Connect specification.


!!! tip

This will be especially useful when you use it in a **large code base** where you use **the same dependencies** over and over again in **many *path operations***.

## To `async` or not to `async`

As dependencies will also be called by **FastAPI** (the same as your *path operation functions*), the same rules apply while defining your functions.