> For the complete documentation index, see [llms.txt](https://mirror-networking.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://mirror-networking.gitbook.io/docs/manual/guides/communications/networkbehaviour-callbacks.md).
# NetworkBehaviour Callbacks
## NetworkBehaviour Callbacks
{% hint style="info" %}
See also [NetworkBehaviour](https://storage.googleapis.com/mirror-api-docs/html/db/d21/class_mirror_1_1_network_behaviour.html) in the API Reference.
{% endhint %}
There are a number of events relating to network behaviours that can occur over the course of a normal multiplayer game. These include events such as the host starting up, a player joining, or a player leaving. Each of these possible events has an associated callback that you can implement in your own code to take action when the event occurs.
When you create a script which inherits from `NetworkBehaviour`, you can write your own implementation of what should happen when these events occur. To do this, you override the virtual methods on the `NetworkBehaviour` class with your own implementation of what should happen when the given event occurs.
This is a full list of virtual methods (callbacks) that you can implement on `NetworkBehaviour`, and where they are called
### Server Only
* OnStartServer
* called when behaviour is spawned on server
* OnStopServer
* called when behaviour is destroyed or unspawned on server
* OnSerialize
* called when behaviour is serialize before it is sent to client, when overriding make sure to call `base.OnSerialize`
### Client only
* OnStartClient
* called when behaviour is spawned on client
* OnStartAuthority
* called when behaviour has authority when it is spawned (eg local player)
* called when behaviour is given authority by the sever
* OnStartLocalPlayer
* called when the behaviour is on the local player object
* OnStopAuthority
* called when authority is taken from the object (eg local player is replaced but not destroyed)
* OnStopClient
* called when object is destroyed on client by the `ObjectDestroyMessage` or `ObjectHideMessage` messages
## Example flows
Below is some example call order for different modes
> NOTE: `Start` is called by unity before the first frame, while normally this happens after Mirror's callbacks. But if you dont call `NetworkServer.Spawn` the same frame as `instantiate` then start may be called first
> Note: `OnRebuildObservers` and `OnSetHostVisibility` is now on `NetworkVisibility` instead of `NetworkBehaviour`
### Server mode
When a NetworkServer.Spawn is called (eg when new client connections and a player is created)
* `OnStartServer`
* `OnRebuildObservers`
* `Start`
### Client mode
When local player is spawned for client
* `OnStartAuthority`
* `OnStartClient`
* `OnStartLocalPlayer`
* `Start`
### Host mode
These are only called on the **Player Game Objects** when a client connects:
* `OnStartServer`
* `OnRebuildObservers`
* `OnStartAuthority`
* `OnStartClient`
* `OnSetHostVisibility`
* `OnStartLocalPlayer`
* `Start`
---
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