# Writing Custom State Behaviours
One of the most powerful components coming with Visual State Machine is the **StateBehaviour** class. It allows you to easily implement the [State Design Pattern](https://gameprogrammingpatterns.com/state.html#the-state-pattern) and create custom MonoBehaviours for your different states. This can for example be used to implement state behaviours for AI characters, game states or UI menus.
```
using Ilumisoft.VisualStateMachine;
using UnityEngine;
///
/// Derive from StateBehaviour to execute custom logic when a state is executed.
///
public class MenuStateBehaviourExample : StateBehaviour
{
///
/// The id of the state the behviour should act on
///
public override string StateID => "Menu";
protected override void OnEnterState()
{
// Execute something when the state is entered
Debug.Log($"On Enter State: '{StateID}'");
}
protected override void OnExitState()
{
// Execute something when the state is exited
Debug.Log($"On Exit State: '{StateID}'");
}
protected override void OnUpdateState()
{
// Execute something when the state is updated...
}
}
```
To use a custom State Behaviour script, simply add it to a Game Object and assign the State Machine it should be executed on.
