diff --git a/en/application-dev/application-models/Readme-EN.md b/en/application-dev/application-models/Readme-EN.md
index b5dd76aea6715dc3bc2e7ad1b8f7cae974343d7c..05cdc41e5d2027e9e3bfba373ed14916b3e790a1 100644
--- a/en/application-dev/application-models/Readme-EN.md
+++ b/en/application-dev/application-models/Readme-EN.md
@@ -17,7 +17,6 @@
     - ExtensionAbility Component
       - [ExtensionAbility Component Overview](extensionability-overview.md)
       - [ServiceExtensionAbility](serviceextensionability.md)
-      - [DataShareExtensionAbility (for System Applications Only)](datashareextensionability.md)
       - [AccessibilityExtensionAbility](accessibilityextensionability.md)
       - [EnterpriseAdminExtensionAbility](enterprise-extensionAbility.md)
       - [InputMethodExtensionAbility](inputmethodextentionability.md)
@@ -37,9 +36,9 @@
             - [Applying Custom Drawing in the Widget](arkts-ui-widget-page-custom-drawing.md)
           - Widget Event Development
             - [Widget Event Capability Overview](arkts-ui-widget-event-overview.md)
+            - [Redirecting to a Specified Page Through the Router Event](arkts-ui-widget-event-router.md)
             - [Updating Widget Content Through FormExtensionAbility](arkts-ui-widget-event-formextensionability.md)
             - [Updating Widget Content Through UIAbility](arkts-ui-widget-event-uiability.md)
-            - [Redirecting to a Specified Page Through the Router Event](arkts-ui-widget-event-router.md)
           - Widget Data Interaction
             - [Widget Data Interaction Overview](arkts-ui-widget-interaction-overview.md)
             - [Configuring a Widget to Update Periodically](arkts-ui-widget-update-by-time.md)
@@ -61,8 +60,9 @@
       - [Continuation Overview](inter-device-interaction-hop-overview.md)
       - [Cross-Device Migration (for System Applications Only)](hop-cross-device-migration.md)
       - [Multi-device Collaboration (for System Applications Only)](hop-multi-device-collaboration.md)
-  - IPC
-    - [Process Model](process-model-stage.md)
+    - [Subscribing to System Environment Variable Changes](subscribe-system-environment-variable-changes.md)
+  - Process Model
+    - [Process Model Overview](process-model-stage.md)
     - Common Events
       - [Introduction to Common Events](common-event-overview.md)
       - Common Event Subscription
@@ -72,14 +72,16 @@
         - [Unsubscribing from Common Events](common-event-unsubscription.md)
       - [Publishing Common Events](common-event-publish.md)
     - [Background Services](background-services.md)
-  - Inter-Thread Communication
-    - [Thread Model](thread-model-stage.md)
+  - Thread Model
+    - [Thread Model Overview](thread-model-stage.md)
     - [Using Emitter for Inter-Thread Communication](itc-with-emitter.md)
     - [Using Worker for Inter-Thread Communication](itc-with-worker.md)
   - Mission Management
     - [Mission Management Scenarios](mission-management-overview.md)
     - [Mission Management and Launch Type](mission-management-launch-type.md)
     - [Page Stack and MissionList](page-mission-stack.md)
+    - [Setting the Icon and Name of a Mission Snapshot](mission-set-icon-name-for-task-snapshot.md)
+  - [Application Configuration File (Stage Model)](config-file-stage.md)
 - FA Model Development
   - [FA Model Development Overview](fa-model-development-overview.md)
   - FA Mode Application Components
@@ -116,12 +118,12 @@
     - [Context](application-context-fa.md)
     - [Want](want-fa.md)
     - [Component Startup Rules](component-startup-rules-fa.md)
-  - IPC
-    - [Process Model](process-model-fa.md)
+  - Process Model
+    - [Process Model Overview](process-model-fa.md)
     - [Common Events](common-event-fa.md)
     - [Background Services](rpc.md)
-  - Inter-Thread Communication
-    - [Thread Model](thread-model-fa.md)
+  - Thread Model
+    - [Thread Model Overview](thread-model-fa.md)
     - [Inter-Thread Communication](itc-fa-overview.md)
   - [Mission Management](mission-management-fa.md)
 - Development of Component Interaction Between the FA Model and Stage Model
diff --git a/en/application-dev/application-models/config-file-stage.md b/en/application-dev/application-models/config-file-stage.md
new file mode 100644
index 0000000000000000000000000000000000000000..66cabf4a99fd4a3f5138c0a8ef1bbf2cefbe15c0
--- /dev/null
+++ b/en/application-dev/application-models/config-file-stage.md
@@ -0,0 +1,6 @@
+# Application Configuration File (Stage Model)
+
+The application configuration file contains information about the application configuration, application components, and permissions, as well as custom information. The information will be provided for the compiler, application market, and operating system in the build, distribution, and running phases.
+
+The application project code developed based on the stage model contains one **app.json5** file and one or more **module.json5** files. For details about common configuration items, see [Application- or Component-Level Configuration (Stage Model)](application-component-configuration-stage.md). For details about the two files, see [Application Configuration File Overview (Stage Model)](../quick-start/application-configuration-file-overview-stage.md).
+
diff --git a/en/application-dev/application-models/figures/mission-and-multiton.png b/en/application-dev/application-models/figures/mission-and-multiton.png
new file mode 100644
index 0000000000000000000000000000000000000000..e50f9d44d475711c17bfe56394fddd8a6c7b784c
Binary files /dev/null and b/en/application-dev/application-models/figures/mission-and-multiton.png differ
diff --git a/en/application-dev/application-models/figures/mission-and-standard.png b/en/application-dev/application-models/figures/mission-and-standard.png
deleted file mode 100644
index feeed48f41371bf22abbee8dbae4695b11ed2514..0000000000000000000000000000000000000000
Binary files a/en/application-dev/application-models/figures/mission-and-standard.png and /dev/null differ
diff --git a/en/application-dev/application-models/figures/mission-list-recent.png b/en/application-dev/application-models/figures/mission-list-recent.png
new file mode 100644
index 0000000000000000000000000000000000000000..bfc35532ad4907fd3a1bfcb61110ed393ea19d1c
Binary files /dev/null and b/en/application-dev/application-models/figures/mission-list-recent.png differ
diff --git a/en/application-dev/application-models/figures/mission-set-task-snapshot-icon.png b/en/application-dev/application-models/figures/mission-set-task-snapshot-icon.png
new file mode 100644
index 0000000000000000000000000000000000000000..9d1ba2503f4e1a5d3b2aafdd93923c3f6c411998
Binary files /dev/null and b/en/application-dev/application-models/figures/mission-set-task-snapshot-icon.png differ
diff --git a/en/application-dev/application-models/figures/mission-set-task-snapshot-label.png b/en/application-dev/application-models/figures/mission-set-task-snapshot-label.png
new file mode 100644
index 0000000000000000000000000000000000000000..c8348685cc0fd521186aa10e8d04495422fc0206
Binary files /dev/null and b/en/application-dev/application-models/figures/mission-set-task-snapshot-label.png differ
diff --git a/en/application-dev/application-models/mission-management-launch-type.md b/en/application-dev/application-models/mission-management-launch-type.md
index 6bad0ba0079e7087406000cd1a5e5ffb54a4f17c..ac8af200aef03876ee9aa9f0f3219f3a856afbbd 100644
--- a/en/application-dev/application-models/mission-management-launch-type.md
+++ b/en/application-dev/application-models/mission-management-launch-type.md
@@ -11,13 +11,13 @@ The following describes how the mission list manager manages the UIAbility insta
   
   ![mission-and-singleton](figures/mission-and-singleton.png)
   
-- **multiton**: Each time **startAbility()** is called, a **UIAbility** instance is created in the application process.
+- **multiton**: Each time [startAbility()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextstartability) is called, a UIAbility instance is created in the application process.
   
   **Figure 2** Missions and multiton mode
   
-  ![mission-and-multiton](figures/mission-and-standard.png)
+  ![mission-and-multiton](figures/mission-and-multiton.png)
   
-- **specified**: The ([onAcceptWant()](../reference/apis/js-apis-app-ability-abilityStage.md#abilitystageonacceptwant)) method of [AbilityStage](abilitystage.md) determines whether to create an instance.
+- **specified**: The ([onAcceptWant()](../reference/apis/js-apis-app-ability-abilityStage.md#abilitystageonacceptwant)) method of [AbilityStage](abilitystage.md) determines whether to create a UIAbility instance.
   
   **Figure 3** Missions and specified mode
   
@@ -33,4 +33,3 @@ Every mission retains a snapshot of the UIAbility instance. After the UIAbility
 > **NOTE**
 >
 > The **specified** mode is supported in the stage model only.
-
diff --git a/en/application-dev/application-models/mission-management-overview.md b/en/application-dev/application-models/mission-management-overview.md
index 8d219cf935b0f4cae4093b33ed760a3603538ecc..785a9f8291ea43e756ebed07843ceef23570160d 100644
--- a/en/application-dev/application-models/mission-management-overview.md
+++ b/en/application-dev/application-models/mission-management-overview.md
@@ -4,7 +4,7 @@
 Before getting started with the development of mission management, be familiar with the following concepts related to mission management:
 
 
-- AbilityRecord: minimum unit for the system service to manage a UIAbility instance. It corresponds to a UIAbility component instance of an application.
+- AbilityRecord: minimum unit for the system service to manage a UIAbility instance. It corresponds to a UIAbility component instance of an application. A maximum of 512 UIAbility instances can be managed on the system service side.
 
 - MissionRecord: minimum unit for mission management. One MissionRecord has only one AbilityRecord. In other words, a UIAbility component instance corresponds to a mission.
 
@@ -13,7 +13,6 @@ Before getting started with the development of mission management, be familiar w
 - MissionListManager: system mission management module that maintains all the MissionLists and is consistent with the list in **Recents**.
   
   **Figure 1** Mission management 
-  
   ![mission-list-manager](figures/mission-list-manager.png)
 
 
@@ -29,102 +28,102 @@ Missions are managed by system applications (such as home screen), rather than t
 - Switch a mission to the foreground.
 
 
-A UIAbility instance corresponds to an independent mission. Therefore, when an application calls **startAbility()** to start a UIAbility, a mission is created.
-
-
-To call [missionManager](../reference/apis/js-apis-application-missionManager.md) to manage missions, the home screen application must request the **ohos.permission.MANAGE_MISSIONS** permission. For details about the configuration, see [Declaring Permissions in the Configuration File](../security/accesstoken-guidelines.md#declaring-permissions-in-the-configuration-file).
-
-
-You can use **missionManager** to manage missions, for example, listening for mission changes, obtaining mission information or snapshots, and clearing, locking, or unlocking missions. The sample code is as follows:
-
-```ts
-import missionManager from '@ohos.app.ability.missionManager'
-
-let listener = {
-    // Listen for mission creation.
-    onMissionCreated: function (mission) {
-        console.info("--------onMissionCreated-------")
-    },
-    // Listen for mission destruction.
-    onMissionDestroyed: function (mission) {
-        console.info("--------onMissionDestroyed-------")
-    },
-    // Listen for mission snapshot changes.
-    onMissionSnapshotChanged: function (mission) {
-        console.info("--------onMissionSnapshotChanged-------")
-    },
-    // Listen for switching the mission to the foreground.
-    onMissionMovedToFront: function (mission) {
-        console.info("--------onMissionMovedToFront-------")
-    },
-    // Listen for mission icon changes.
-    onMissionIconUpdated: function (mission, icon) {
-        console.info("--------onMissionIconUpdated-------")
-    },
-    // Listen for mission name changes.
-    onMissionLabelUpdated: function (mission) {
-        console.info("--------onMissionLabelUpdated-------")
-    },
-    // Listen for mission closure events.
-    onMissionClosed: function (mission) {
-        console.info("--------onMissionClosed-------")
-    }
-};
-
-// 1. Register a mission change listener.
-let listenerId = missionManager.on('mission', listener);
-
-// 2. Obtain the latest 20 missions in the system.
-missionManager.getMissionInfos("", 20, (error, missions) => {
-    console.info("getMissionInfos is called, error.code = " + error.code);
-    console.info("size = " + missions.length);
-    console.info("missions = " + JSON.stringify(missions));
-});
-
-// 3. Obtain the detailed information about a mission.
-let missionId = 11; // The mission ID 11 is only an example.
-let mission = missionManager.getMissionInfo("", missionId).catch(function (err) {
-    console.info(err);
-});
-
-// 4. Obtain the mission snapshot.
-missionManager.getMissionSnapShot("", missionId, (error, snapshot) => {
-    console.info("getMissionSnapShot is called, error.code = " + error.code);
-    console.info("bundleName = " + snapshot.ability.bundleName);
-})
-
-// 5. Obtain the low-resolution mission snapshot.
-missionManager.getLowResolutionMissionSnapShot("", missionId, (error, snapshot) => {
-    console.info("getLowResolutionMissionSnapShot is called, error.code = " + error.code);
-    console.info("bundleName = " + snapshot.ability.bundleName);
-})
-
-// 6. Lock or unlock the mission.
-missionManager.lockMission(missionId).then(() => {
-    console.info("lockMission is called ");
-});
-
-missionManager.unlockMission(missionId).then(() => {
-    console.info("unlockMission is called ");
-});
-
-// 7. Switch the mission to the foreground.
-missionManager.moveMissionToFront(missionId).then(() => {
-    console.info("moveMissionToFront is called ");
-});
-
-// 8. Clear a single mission.
-missionManager.clearMission(missionId).then(() => {
-    console.info("clearMission is called ");
-});
-
-// 9. Clear all missions.
-missionManager.clearAllMissions().catch(function (err) {
-    console.info(err);
-});
-
-// 10. Deregister the mission change listener.
-missionManager.off('mission', listenerId, (error) => {
-    console.info("unregisterMissionListener");
-})
-```
+A UIAbility instance corresponds to an independent mission. Therefore, when an application calls [startAbility()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextstartability) to start a UIAbility, a mission is created.
+
+1. To call [missionManager](../reference/apis/js-apis-application-missionManager.md) to manage missions, the home screen application must request the **ohos.permission.MANAGE_MISSIONS** permission. For details about the configuration, see [Declaring Permissions in the Configuration File](../security/accesstoken-guidelines.md#declaring-permissions-in-the-configuration-file).
+
+2. You can use **missionManager** to manage missions, for example, listening for mission changes, obtaining mission information or snapshots, and clearing, locking, or unlocking missions.
+
+   ```ts
+   import missionManager from '@ohos.app.ability.missionManager'
+   
+   let listener = {
+     // Listen for mission creation.
+     onMissionCreated: function (mission) {
+       console.info("--------onMissionCreated-------")
+     },
+     // Listen for mission destruction.
+     onMissionDestroyed: function (mission) {
+       console.info("--------onMissionDestroyed-------")
+     },
+     // Listen for mission snapshot changes.
+     onMissionSnapshotChanged: function (mission) {
+       console.info("--------onMissionSnapshotChanged-------")
+     },
+     // Listen for switching the mission to the foreground.
+     onMissionMovedToFront: function (mission) {
+       console.info("--------onMissionMovedToFront-------")
+     },
+     // Listen for mission icon changes.
+     onMissionIconUpdated: function (mission, icon) {
+       console.info("--------onMissionIconUpdated-------")
+     },
+     // Listen for mission name changes.
+     onMissionLabelUpdated: function (mission) {
+       console.info("--------onMissionLabelUpdated-------")
+     },
+     // Listen for mission closure events.
+     onMissionClosed: function (mission) {
+       console.info("--------onMissionClosed-------")
+     }
+   };
+   
+   // 1. Register a mission change listener.
+   let listenerId = missionManager.on('mission', listener);
+   
+   // 2. Obtain the latest 20 missions in the system.
+   missionManager.getMissionInfos("", 20, (error, missions) => {
+     console.info("getMissionInfos is called, error.code = " + error.code);
+     console.info("size = " + missions.length);
+     console.info("missions = " + JSON.stringify(missions));
+   });
+   
+   // 3. Obtain the detailed information about a mission.
+   let missionId = 11; // The mission ID 11 is only an example.
+   let mission = missionManager.getMissionInfo("", missionId).catch(function (err) {
+     console.info(err);
+   });
+   
+   // 4. Obtain the mission snapshot.
+   missionManager.getMissionSnapShot("", missionId, (error, snapshot) => {
+     console.info("getMissionSnapShot is called, error.code = " + error.code);
+     console.info("bundleName = " + snapshot.ability.bundleName);
+   })
+   
+   // 5. Obtain the low-resolution mission snapshot.
+   missionManager.getLowResolutionMissionSnapShot("", missionId, (error, snapshot) => {
+     console.info("getLowResolutionMissionSnapShot is called, error.code = " + error.code);
+     console.info("bundleName = " + snapshot.ability.bundleName);
+   })
+   
+   // 6. Lock or unlock the mission.
+   missionManager.lockMission(missionId).then(() => {
+     console.info("lockMission is called ");
+   });
+   
+   missionManager.unlockMission(missionId).then(() => {
+     console.info("unlockMission is called ");
+   });
+   
+   // 7. Switch the mission to the foreground.
+   missionManager.moveMissionToFront(missionId).then(() => {
+     console.info("moveMissionToFront is called ");
+   });
+   
+   // 8. Clear a single mission.
+   missionManager.clearMission(missionId).then(() => {
+     console.info("clearMission is called ");
+   });
+   
+   // 9. Clear all missions.
+   missionManager.clearAllMissions().catch(function (err) {
+     console.info(err);
+   });
+   
+   // 10. Deregister the mission change listener.
+   missionManager.off('mission', listenerId, (error) => {
+     console.info("unregisterMissionListener");
+   })
+   ```
+
+   
diff --git a/en/application-dev/application-models/mission-set-icon-name-for-task-snapshot.md b/en/application-dev/application-models/mission-set-icon-name-for-task-snapshot.md
new file mode 100644
index 0000000000000000000000000000000000000000..c98d39ff8348f330d58138db89afcc2a0d5995ca
--- /dev/null
+++ b/en/application-dev/application-models/mission-set-icon-name-for-task-snapshot.md
@@ -0,0 +1,51 @@
+# Setting the Icon and Name of a Mission Snapshot
+
+Setting a unique icon and name for each mission snapshot of an application helps you better manage the missions and functions of the application.
+
+By default, the **icon** and **label** fields in the [abilities tag](../quick-start/module-configuration-file.md#abilities) of the [module.json5 file](../quick-start/module-configuration-file.md) are used to set the icon and label.
+
+Figure 1 Mission snapshot of a UIAbility
+
+![](figures/mission-list-recent.png)
+
+You can also use [UIAbilityContext.setMissionIcon()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextsetmissionicon) and [UIAbilityContext.setMissionLabel()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextsetmissionlabel) to customize the icon and name for a mission snapshot. For example, for a UIAbility instance in multiton mode, you can configure the icon and name for each mission snapshot based on different functions.
+
+This document describes the following operations:
+
+- [Setting a Mission Snapshot Icon (for System Applications Only)](#setting-a-mission-snapshot-icon-for-system-applications-only)
+- [Setting a Mission Snapshot Name](#setting-a-mission-snapshot-name)
+
+## Setting a Mission Snapshot Icon (for System Applications Only)
+
+Call [UIAbilityContext.setMissionIcon()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextsetmissionicon) to set the icon of a mission snapshot. The icon is an object of the [PixelMap](../reference/apis/js-apis-image.md#pixelmap7) type. For details about how to obtain the context, see [Obtaining the Context of UIAbility](uiability-usage.md#obtaining-the-context-of-uiability).
+```ts
+let imagePixelMap: PixelMap = undefined; // Obtain the PixelMap information.
+
+this.context.setMissionIcon(imagePixelMap, (err) => {
+  console.error(`setMissionLabel failed, code is ${err.code}, message is ${err.message}`);
+})
+```
+
+The display effect is shown below.
+
+Figure 2 Mission snapshot icon
+
+![](figures/mission-set-task-snapshot-icon.png)
+
+## Setting a Mission Snapshot Name
+
+Call [UIAbilityContext.setMissionLabel()](../reference/apis/js-apis-inner-application-uiAbilityContext.md#uiabilitycontextsetmissionlabel) to set the name of a mission snapshot.
+
+```ts
+this.context.setMissionLabel('test').then(() => {
+  console.info('setMissionLabel succeeded.');
+}).catch((err) => {
+  console.error(`setMissionLabel failed, code is ${err.code}, message is ${err.message}`);
+});
+```
+
+The display effect is shown below.
+
+Figure 3 Mission snapshot name
+
+![](figures/mission-set-task-snapshot-label.png)
diff --git a/en/application-dev/application-models/process-model-fa.md b/en/application-dev/application-models/process-model-fa.md
index 699643031121521fbf95d26a949df906fa175a18..ce4c9778d3bf678c7ecb8094477050a42eebb7d7 100644
--- a/en/application-dev/application-models/process-model-fa.md
+++ b/en/application-dev/application-models/process-model-fa.md
@@ -1,4 +1,4 @@
-# Process Model (FA Model)
+# Process Model Overview (FA Model)
 
 
 The OpenHarmony process model is shown below.
diff --git a/en/application-dev/application-models/process-model-stage.md b/en/application-dev/application-models/process-model-stage.md
index 03da480722de124a1ede58da52e74cd48c5f23f0..cf758d94636773dfd190366d0e215de655902abd 100644
--- a/en/application-dev/application-models/process-model-stage.md
+++ b/en/application-dev/application-models/process-model-stage.md
@@ -1,4 +1,4 @@
-# Process Model (Stage Model)
+# Process Model Overview (Stage Model)
 
 
 The OpenHarmony process model is shown below.
diff --git a/en/application-dev/application-models/subscribe-system-environment-variable-changes.md b/en/application-dev/application-models/subscribe-system-environment-variable-changes.md
new file mode 100644
index 0000000000000000000000000000000000000000..c231f483e9bcd8f83faf49d40007730d0f854de5
--- /dev/null
+++ b/en/application-dev/application-models/subscribe-system-environment-variable-changes.md
@@ -0,0 +1,172 @@
+# Subscribing to System Environment Variable Changes
+
+System environment variables are system settings (for example, the system language or screen direction) of a device that may change during the running of an application.
+
+By subscribing to the changes of system environment variables, the application can detect the changes in a timely manner and process the changes accordingly, providing better user experience. For example, when the system language changes, the application can display the UI in the new language; when the user rotates the device to landscape or portrait mode, the application can re-arrange the UI to adapt to the new screen orientation and size.
+
+The system environment variable changes are usually triggered by options in **Settings** or icons in **Control Panel**. For details about the system environment variables that support subscription, see [Configuration](../reference/apis/js-apis-app-ability-configuration.md).
+
+In OpenHarmony, you can subscribe to system environment variable changes in the following ways:
+
+- [Using ApplicationContext for Subscription](#using-applicationcontext-for-subscription)
+- [Using AbilityStage for Subscription](#using-abilitystage-for-subscription)
+- [Using UIAbility for Subscription](#using-uiability-for-subscription)
+- [Using ExtensionAbility for Subscription](#using-extensionability-for-subscription)
+
+## Using ApplicationContext for Subscription
+
+[ApplicationContext](../reference/apis/js-apis-inner-application-applicationContext.md) provides an API for registering a callback function to subscribe to the system environment variable changes. It also provides an API for deregistration so you can release related resources when they are no longer needed.
+
+1. Call **ApplicationContext.on(type: 'environment', callback: EnvironmentCallback)** to subscribe to changes in system environment variables. The code snippet below is used to subscribe to system language changes on a page.
+
+   ```ts
+   import common from '@ohos.app.ability.common';
+   
+   @Entry
+   @Component
+   struct Index {
+     private context = getContext(this) as common.UIAbilityContext;
+     private callbackId: number; // ID of the subscription for system environment variable changes.
+   
+     subscribeConfigurationUpdate() {
+       let systemLanguage: string = this.context.config.language; // Obtain the system language in use.
+   
+       // 1. Obtain an ApplicationContext object.
+       let applicationContext = this.context.getApplicationContext();
+   
+       // 2. Subscribe to system environment variable changes through ApplicationContext.
+       let environmentCallback = {
+         onConfigurationUpdated(newConfig) {
+           console.info(`onConfigurationUpdated systemLanguage is ${systemLanguage}, newConfig: ${JSON.stringify(newConfig)}`);
+   
+           if (this.systemLanguage !== newConfig.language) {
+             console.info(`systemLanguage from ${systemLanguage} changed to ${newConfig.language}`);
+             systemLanguage = newConfig.language; // Save the new system language as the system language in use, which will be used for comparison.
+           }
+         },
+         onMemoryLevel(level) {
+           console.info(`onMemoryLevel level: ${level}`);
+         }
+       }
+   
+       this.callbackId = applicationContext.on('environment', environmentCallback);
+     }
+   
+     // Page display.
+     build() {
+       // ...
+     }
+   }
+   ```
+
+2. Call **ApplicationContext.off(type: 'environment', callbackId: number)** to release the resources.
+
+   ```ts
+   import common from '@ohos.app.ability.common';
+   
+   @Entry
+   @Component
+   struct Index {
+     private context = getContext(this) as common.UIAbilityContext;
+     private callbackId: number; // ID of the subscription for system environment variable changes.
+   
+     unsubscribeConfigurationUpdate() {
+       let applicationContext = this.context.getApplicationContext();
+       applicationContext.off('environment', this.callbackId);
+     }
+   
+     // Page display.
+     build() {
+       // ...
+     }
+   }
+   ```
+
+## Using AbilityStage for Subscription
+
+The AbilityStage component provides the [AbilityStage.onConfigurationUpdate()](../reference/apis/js-apis-app-ability-abilityStage.md#abilitystageonconfigurationupdate) callback for subscribing to system environment variable changes. This callback is invoked when a system environment variable changes. In this callback, the latest system environment configuration is obtained through the [Configuration](../reference/apis/js-apis-app-ability-configuration.md) object.  
+
+> **NOTE**
+>
+> - AbilityStage is not automatically generated in the default project of DevEco Studio. For details about how to create an AbilityStage file, see [AbilityStage Component Container](abilitystage.md).
+> - The callback used to subscribe to system environment variable changes has the same lifecycle as the [AbilityStage](../reference/apis/js-apis-app-ability-abilityStage.md) instance and will be destroyed when the instance is destroyed.
+
+The code snippet below uses the [AbilityStage.onConfigurationUpdate()](../reference/apis/js-apis-app-ability-abilityStage.md#abilitystageonconfigurationupdate) callback to subscribe to the system language changes.
+
+```ts
+import AbilityStage from '@ohos.app.ability.AbilityStage';
+
+let systemLanguage: string; // System language in use.
+
+export default class MyAbilityStage extends AbilityStage {
+    onCreate() {
+        systemLanguage = this.context.config.language; // Obtain the system language in use when the AbilityStage instance is loaded for the first time.
+        console.info(`systemLanguage is ${systemLanguage} `);
+    }
+
+    onConfigurationUpdate(newConfig) {
+        console.info(`onConfigurationUpdated systemLanguage is ${systemLanguage}, newConfig: ${JSON.stringify(newConfig)}`);
+
+        if (systemLanguage !== newConfig.language) {
+            console.info(`systemLanguage from ${systemLanguage} changed to ${newConfig.language}`);
+            systemLanguage = newConfig.language; // Save the new system language as the system language in use, which will be used for comparison.
+        }
+    }
+}
+```
+
+## Using UIAbility for Subscription
+
+The UIAbility component provides the **UIAbility.onConfigurationUpdate()** callback for subscribing to system environment variable changes. This callback is invoked when a system environment variable changes. In this callback, the latest system environment configuration is obtained through the [Configuration](../reference/apis/js-apis-app-ability-configuration.md) object, without restarting the UIAbility.
+
+> **NOTE**
+>
+> The callback used to subscribe to system environment variable changes has the same lifecycle as the UIAbility instance and will be destroyed when the instance is destroyed.
+
+The code snippet below uses the **onConfigurationUpdate()** callback to subscribe to the system language changes.
+
+```ts
+import UIAbility from '@ohos.app.ability.UIAbility';
+
+let systemLanguage: string; // System language in use.
+
+export default class EntryAbility extends UIAbility {
+    onCreate(want, launchParam) {
+        systemLanguage = this.context.config.language; // Obtain the system language in use when the UIAbility instance is loaded for the first time.
+        console.info(`systemLanguage is ${systemLanguage} `);
+    }
+
+    onConfigurationUpdate(newConfig) {
+        console.info(`onConfigurationUpdated systemLanguage is ${systemLanguage}, newConfig: ${JSON.stringify(newConfig)}`);
+
+        if (systemLanguage !== newConfig.language) {
+            console.info(`systemLanguage from ${systemLanguage} changed to ${newConfig.language}`);
+            systemLanguage = newConfig.language; // Save the new system language as the system language in use, which will be used for comparison.
+        }
+    }
+
+    // ...
+}
+```
+
+## Using ExtensionAbility for Subscription
+
+The ExtensionAbility component provides the **onConfigurationUpdate()** callback for subscribing system environment variable changes. This callback is invoked when a system environment variable changes. In this callback, the latest system environment configuration is obtained through the [Configuration](../reference/apis/js-apis-app-ability-configuration.md) object.
+
+> **NOTE**
+>
+> The callback used to subscribe to system environment variable changes has the same lifecycle as the ExtensionAbility instance and will be destroyed when the instance is destroyed.
+
+The code snippet below uses FormExtensionAbility as an example to describe how to use the **onConfigurationUpdate()** callback to subscribe to system environment variable changes.
+
+```ts
+import FormExtensionAbility from '@ohos.app.form.FormExtensionAbility';
+
+export default class EntryFormAbility extends FormExtensionAbility {
+    onConfigurationUpdate(newConfig) {
+        console.info(`newConfig is ${JSON.stringify(newConfig)}`);
+    }
+
+    // ...
+}
+```
diff --git a/en/application-dev/application-models/thread-model-fa.md b/en/application-dev/application-models/thread-model-fa.md
index 56cf8c94732acede5ee03cf9f9b79553e0183b49..0f11cddb48792e887a14a2d5011dbdcd4736340d 100644
--- a/en/application-dev/application-models/thread-model-fa.md
+++ b/en/application-dev/application-models/thread-model-fa.md
@@ -1,4 +1,4 @@
-# Thread Model (FA Model)
+# Thread Model Overview (FA Model)
 
 
 There are three types of threads in the FA model:
diff --git a/en/application-dev/application-models/thread-model-stage.md b/en/application-dev/application-models/thread-model-stage.md
index 4ca9fb3ed369f78cf12054c7b6da085b8640b1db..7343b9b619a5d68354e65e254a22a2b078ca44ee 100644
--- a/en/application-dev/application-models/thread-model-stage.md
+++ b/en/application-dev/application-models/thread-model-stage.md
@@ -1,4 +1,4 @@
-# Thread Model (Stage Model)
+# Thread Model Overview (Stage Model)
 
 For an OpenHarmony application, each process has a main thread to provide the following functionalities: