# yii\di

> 4 classes of the yii\di namespace.

[API reference](/docs/api/index.md) › [yii](/docs/api/yii/index.md) › di

## Classes

| Class | Summary |
| --- | --- |
| [`Container`](/docs/api/yii/di/container/index.md) | Container implements a [dependency injection](https://en.wikipedia.org/wiki/Dependency_injection) container. |
| [`Instance`](/docs/api/yii/di/instance/index.md) | Instance represents a reference to a named object in a dependency injection (DI) container or a service locator. |
| [`NotInstantiableException`](/docs/api/yii/di/notinstantiableexception/index.md) | NotInstantiableException represents an exception caused by incorrect dependency injection container configuration or usage. |
| [`ServiceLocator`](/docs/api/yii/di/servicelocator/index.md) | ServiceLocator implements a [service locator](https://en.wikipedia.org/wiki/Service_locator_pattern). |