# Introduction to Unity Properties

> Understand the fundamentals and uses of the Unity Properties API.

Unity Properties is a system that allows you to explore and modify the properties of C# types at runtime. It uses a visitor-style API that traverses the properties of an object graph in a predictable, controllable way.

You can use Unity Properties to read from or write to C# types generically, with minimal type-specific handling. This allows you to work with custom, user-defined C# types and, for example, to validate them, or convert them between different representations.

Unity Properties makes it possible to avoid or minimize [reflection](https://learn.microsoft.com/en-us/dotnet/fundamentals/reflection/reflection), which is relatively slow, allocates memory (which increases garbage collector overhead), and has limited support, especially on platforms that require ahead-of-time (AOT) compilation with [IL2CPP](/engine/6000.3/manual/scripting/compilation-and-code-reload/script-compilation/backends/il2cpp.md).

Unity Properties can be useful for the following common scenarios:

* Data validation and processing:

  * Traverse an object graph to validate ranges, nulls, references, or enforce constraints.
  * Compute diffs, hashes, or change detection across properties.

* Copying, cloning, and patching:
  * Deep copy containers or apply patches by visiting and copying specific properties.

* Authoring-to-runtime data conversion:
  * For example, converting ScriptableObject configuration data into runtime structs) via property traversal.

## Fundamental features

The Unity Properties framework has the following fundamental features that you can use to handle C# type data generically:

* [Property bags](/engine/6000.3/manual/scripting/object-oriented-development/properties/property-bags.md): An [`IPropertyBag<T>`](/engine/6000.3/script-reference/unity/properties/ipropertybag1.md) describes the fields and properties of type `T`. Unity generates property bags so the system can enumerate properties of your type.
* [Visitors](/engine/6000.3/manual/scripting/object-oriented-development/properties/property-visitors.md): You implement a visitor with callbacks like [`Visit<TContainer, TValue>`](/engine/6000.3/script-reference/unity/properties/ipropertyvisitor/visit.md). The framework traverses the container's properties and invokes your logic per property.
* Adapters: Hooks that customize how specific types are visited or converted (for example, special handling for `Vector3`, enums, collections).
* [Property paths and traversal](/engine/6000.3/manual/scripting/object-oriented-development/properties/property-paths.md): Support for nested containers, arrays, dictionaries, and addressing values via paths with controlled depth and options.

For more detailed examples that use these features together, refer to [Use `PropertyVisitor` to create a property visitor](/engine/6000.3/manual/scripting/object-oriented-development/properties/property-visitors-property-visitor.md) and [Use low level APIs to create a property visitor](/engine/6000.3/manual/scripting/object-oriented-development/properties/property-visitors-low-level-api.md).

## Additional resources

* [Property bags](/engine/6000.3/manual/scripting/object-oriented-development/properties/property-bags.md)
* [Property visitors](/engine/6000.3/manual/scripting/object-oriented-development/properties/property-visitors.md)
* [Property paths](/engine/6000.3/manual/scripting/object-oriented-development/properties/property-paths.md)
* [Use `PropertyVisitor` to create a property visitor](/engine/6000.3/manual/scripting/object-oriented-development/properties/property-visitors-property-visitor.md)
* [Use low level APIs to create a property visitor](/engine/6000.3/manual/scripting/object-oriented-development/properties/property-visitors-low-level-api.md)