> For the complete documentation index, see [llms.txt](https://docs.coherence.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.coherence.io/0.9/connected-entities/overview.md).

# Overview

Sometimes you want to synchronize Entities that are connected to other Entities. These relationships can be references between Entities, but they can also involve direct parent-child relationship between game objects, or more nuanced use cases.

Here's a guide for what technique to use, depending on the situation:

* If you have an Entity that needs to keep a nullable reference to another Entity, use a normal [Entity reference](/0.9/connected-entities/entity-references.md). This includes any existing MonoBehaviour that has GameObject or Transform fields that you want to synchronize over the network.
* If the Entities are placed in a hierarchy, use the techniques for [parent-child relationships](/0.9/connected-entities/parent-child.md).