Edited; very clean!

docs/guide/concept-service-locator.md

@@ -2,19 +2,19 @@ Service Locator
 ===============
 
 A service locator is an object that knows how to provide all sorts of services (or components) that an application
-might need. Within a service locator, each component has only a single instance which is uniquely identified by an ID.
+might need. Within a service locator, each component exists as only a single instance, uniquely identified by an ID.
 You use the ID to retrieve a component from the service locator.
 
-In Yii, a service locator is simply an instance of [[yii\di\ServiceLocator]] or its child class.
+In Yii, a service locator is simply an instance of [[yii\di\ServiceLocator]], or from a child class.
 
-The most commonly used service locator in Yii is the *application* object which can be accessed through
-`\Yii::$app`. The services it provides are called *application components*, such as the `request`, `response`,
-`urlManager` components. You may configure these components or even replace them with your own implementations easily
+The most commonly used service locator in Yii is the *application* object, which can be accessed through
+`\Yii::$app`. The services it provides are called *application components*, such as the `request`, `response`, and
+`urlManager` components. You may configure these components, or even replace them with your own implementations, easily
 through functionality provided by the service locator.
 
 Besides the application object, each module object is also a service locator.
 
-To use a service locator, the first step is to register components. A component can be registered
+To use a service locator, the first step is to register components with it. A component can be registered
 via [[yii\di\ServiceLocator::set()]]. The following code shows different ways of registering components:
 
 ```php
@@ -43,7 +43,7 @@ $locator->set('search', function () {
 $locator->set('pageCache', new FileCache);
 ```
 
-Once a component is registered, you can access it using its ID in one of the following two ways:
+Once a component has been registered, you can access it using its ID, in one of the two following ways:
 
 ```php
 $cache = $locator->get('cache');
@@ -53,7 +53,7 @@ $cache = $locator->cache;
 
 As shown above, [[yii\di\ServiceLocator]] allows you to access a component like a property using the component ID.
 When you access a component for the first time, [[yii\di\ServiceLocator]] will use the component registration
-information to create a new instance of the component and return it. Later if the component is accessed again,
+information to create a new instance of the component and return it. Later, if the component is accessed again,
 the service locator will return the same instance.
 
 You may use [[yii\di\ServiceLocator::has()]] to check if a component ID has already been registered.
@@ -61,9 +61,8 @@ If you call [[yii\di\ServiceLocator::get()]] with an invalid ID, an exception wi
 
 
 Because service locators are often being created with [configurations](concept-configurations.md),
-a writable property named [[yii\di\ServiceLocator::setComponents()|components]] is provided so that
-you can configure it and register multiple components at once. The following code shows a configuration array
-that can be used to configure an application and register the "db", "cache" and "search" components:
+a writable property named [[yii\di\ServiceLocator::setComponents()|components]] is provided. This allows you to configure and register multiple components at once. The following code shows a configuration array
+that can be used to configure an application, while also registering the "db", "cache" and "search" components:
 
 ```php
 return [