# Update()

> Update the World's default system groups.

## Definition

* **Type:** Method
* **Namespace:** [Unity.Entities](/engine/7000.0/script-reference/unity/entities.md)
* **Assembly:** UnityEngine.EntitiesModule

```csharp
public void Update()
```

### Remarks

The system group update order is:

1. [InitializationSystemGroup](/engine/7000.0/script-reference/unity/entities/initializationsystemgroup.md)
2. [SimulationSystemGroup](/engine/7000.0/script-reference/unity/entities/simulationsystemgroup.md)
3. [PresentationSystemGroup](/engine/7000.0/script-reference/unity/entities/presentationsystemgroup.md)

Generally this is not necessary within the context of a UnityEngine application; instead, use AppendWorldToPlayerLoop to insert these system groups into the UnityEngine player loop, where they'll be interleaved with existing UnityEngine updates.