The OpenHarmony application framework has two models: Feature Ability (FA) model and stage model. Correspondingly, there are two sets of context mechanisms. **application/BaseContext** is a common context base class. It uses the **stageMode** attribute to specify whether the context is used for the stage model.
- FA model
Only the methods in **app/Context** can be used for the context in the FA model. Both the application-level context and ability-level context are instances of this type. If an ability-level method is invoked in the application-level context, an error occurs. Therefore, you must pay attention to the actual meaning of the **Context** instance.
- Stage model
The stage model has the following types of contexts: **application/Context**, **application/ApplicationContext**, **application/AbilityStageContext**, **application/ExtensionContext**, **application/AbilityContext**, and **application/FormExtensionContext**. For details about these contexts and how to use them, see [Context in the Stage Model](#context-in-the-stage-model).
