diff --git a/docs/en/Application-Services.md b/docs/en/Application-Services.md
index d28a7290fb..9cfec614cb 100644
--- a/docs/en/Application-Services.md
+++ b/docs/en/Application-Services.md
@@ -367,6 +367,84 @@ public class DistrictKey
 }
 ````
 
+### Authorization (for CRUD App Services)
+
+There are two ways of authorizing the base application service methods;
+
+1. You can set the policy properties (xxxPolicyName) in the constructor of your service. Example:
+
+```csharp
+public class MyPeopleAppService : CrudAppService<Person, PersonDto, Guid>
+{
+    public MyPeopleAppService(IRepository<Person, Guid> repository) 
+        : base(repository)
+    {
+        GetPolicyName = "...";
+        GetListPolicyName = "...";
+        CreatePolicyName = "...";
+        UpdatePolicyName = "...";
+        DeletePolicyName = "...";
+    }
+}
+```
+
+`CreatePolicyName` is checked by the `CreateAsync` method and so on... You should specify a policy (permission) name defined in your application.
+
+2. You can override the check methods (CheckXxxPolicyAsync) in your service. Example:
+
+```csharp
+public class MyPeopleAppService : CrudAppService<Person, PersonDto, Guid>
+{
+    public MyPeopleAppService(IRepository<Person, Guid> repository) 
+        : base(repository)
+    {
+    }
+
+    protected override async Task CheckDeletePolicyAsync()
+    {
+        await AuthorizationService.CheckAsync("...");
+    }
+}
+```
+
+You can perform any logic in the `CheckDeletePolicyAsync` method. It is expected to throw an `AbpAuthorizationException` in any unauthorized case, like `AuthorizationService.CheckAsync` already does.
+
+### Base Properties & Methods
+
+CRUD application service base class provides many useful base methods that **you can override** to customize it based on your requirements.
+
+#### CRUD Methods
+
+These are the essential CRUD methods. You can override any of them to completely customize the operation. Here, the definitions of the methods:
+
+````csharp
+Task<TGetOutputDto> GetAsync(TKey id);
+Task<PagedResultDto<TGetListOutputDto>> GetListAsync(TGetListInput input);
+Task<TGetOutputDto> CreateAsync(TCreateInput input);
+Task<TGetOutputDto> UpdateAsync(TKey id, TUpdateInput input);
+Task DeleteAsync(TKey id);
+````
+
+#### Querying
+
+These methods are low level methods those can be control how to query entities from the database.
+
+* `CreateFilteredQuery` can be overridden to create an `IQueryable<TEntity>` that is filtered by the given input. If your `TGetListInput` class contains any filter, it is proper to override this method and filter the query. It returns the (unfiltered) repository (which is already `IQueryable<TEntity>`) by default.
+* `ApplyPaging` is used to make paging on the query. If your `TGetListInput` already implements `IPagedResultRequest`, you don't need to override this since the ABP Framework automatically understands it and performs the paging.
+* `ApplySorting` is used to sort (order by...) the query. If your `TGetListInput` already implements the `ISortedResultRequest`, ABP Framework automatically sorts the query. If not, it fallbacks to the `ApplyDefaultSorting` which tries to sort by creating time, if your entity implements the standard `IHasCreationTime` interface.
+* `GetEntityByIdAsync` is used to get an entity by id, which calls `Repository.GetAsync(id)` by default.
+* `DeleteByIdAsync` is used to delete an entity by id, which calls `Repository.DeleteAsync(id)` by default.
+
+#### Object to Object Mapping
+
+These methods are used to convert Entities to DTOs and vice verse. They uses the [IObjectMapper](Object-To-Object-Mapping.md) by default.
+
+* `MapToGetOutputDtoAsync` is used to map the entity to the DTO returned from the `GetAsync`, `CreateAsync` and `UpdateAsync` methods. Alternatively, you can override the `MapToGetOutputDto` if you don't need to perform any async operation.
+* `MapToGetListOutputDtosAsync` is used to map a list of entities to a list of DTOs returned from the `GetListAsync` method. It uses the `MapToGetListOutputDtoAsync` to map each entity in the list. You can override one of them based on your case. Alternatively, you can override the `MapToGetListOutputDto` if you don't need to perform any async operation.
+* `MapToEntityAsync` method has two overloads;
+  * `MapToEntityAsync(TCreateInput)` is used to create an entity from `TCreateInput`.
+  * `MapToEntityAsync(TUpdateInput, TEntity)` is used to update an existing entity from `TUpdateInput`.
+
 ## Lifetime
 
 Lifetime of application services are [transient](Dependency-Injection.md) and they are automatically registered to the dependency injection system.