diff --git a/docs/guide/concept-di-container.md b/docs/guide/concept-di-container.md
index 57b35e18af..bcb32b52c1 100644
--- a/docs/guide/concept-di-container.md
+++ b/docs/guide/concept-di-container.md
@@ -15,6 +15,7 @@ dependency injection:
 * Constructor injection;
 * Setter and property injection;
 * PHP callable injection.
+* Controller action injection.
 
 
 ### Constructor Injection <span id="constructor-injection"></span>
@@ -116,10 +117,12 @@ $foo = $container->get('Foo');
 By doing so, the person who wants to configure the `Foo` class no longer needs to be aware of how it is built.
 
 
-### Controller action injection
+### Controller action injection <span id="controller-action-injection"></span>
 
-Controller action injection is a special type of DI where dependecies are resolved per action which is useful for
-keeping dependencies number low in MVC controllers.
+Controller action injection is a special type of DI where dependecies are declared using the type hints of
+method signature and resolved in the runtime when the action is acturally called. It is useful for keeping
+the MVC controllers slim and light-weighted since it doesn't require you to configure all the possible dependencies
+of the controller beforehand.
 
 ```php
 public function actionSend($email, EmailValidator $validator)