diff --git a/source/general/core_classes.rst b/source/general/core_classes.rst
index 07c0b00..1dd6bb2 100644
--- a/source/general/core_classes.rst
+++ b/source/general/core_classes.rst
@@ -1,24 +1,17 @@
 ############################
-Creating Core System Classes
+新增系統核心類別
 ############################
 
-Every time CodeIgniter runs there are several base classes that are
-initialized automatically as part of the core framework. It is possible,
-however, to swap any of the core system classes with your own versions
-or even extend the core versions.
+每次 CodeIgniter 執行時，有幾個基礎類別會自動初始化，成為核心框架的一部分。不過還是有可能用你自己的版本來置換甚至擴充這些系統核心類別。
 
-**Most users will never have any need to do this, but the option to
-replace or extend them does exist for those who would like to
-significantly alter the CodeIgniter core.**
+**大部分的使用者永遠不會需要這樣做，但是這個選項還是保留給那些想要大幅置換或擴充 CodeIgniter 核心的人。**
 
-.. note:: Messing with a core system class has a lot of implications, so
-	make sure you know what you are doing before attempting it.
+.. note:: 介入核心系統可能引發許多隱藏的問題，所以請在這麼做之前確定你知道你自己在做什麼。
 
-System Class List
+系統類別列表
 =================
 
-The following is a list of the core system files that are invoked every
-time CodeIgniter runs:
+以下是一個系統核心檔案的清單，每次 CodeIgniter 執行時都會呼叫他們： :
 
 -  Benchmark
 -  Config
@@ -35,48 +28,40 @@ time CodeIgniter runs:
 -  URI
 -  Utf8
 
-Replacing Core Classes
+更換核心類別
 ======================
 
-To use one of your own system classes instead of a default one simply
-place your version inside your local *application/core/* directory::
+要用你自己的系統核心類別來置換預設的，只要將你自己的版本放在 *application/core* 目錄裡： ::
 
 	application/core/some_class.php
 
-If this directory does not exist you can create it.
+如果這個目錄不存在，你可以自己新增。
 
-Any file named identically to one from the list above will be used
-instead of the one normally used.
+任何與在上述清單中檔案名稱相符的檔案都會被載入，取代系統正常使用的。
 
-Please note that your class must use CI as a prefix. For example, if
-your file is named Input.php the class will be named::
+請注意，你的類別名稱必須使用 CI 作為前置字串。例如，如果你的檔案名稱是 Input.php ，那類別名稱將是： ::
 
 	class CI_Input {
 
 	}
 
-Extending Core Class
+繼承核心類別
 ====================
 
-If all you need to do is add some functionality to an existing library -
-perhaps add a method or two - then it's overkill to replace the entire
-library with your version. In this case it's better to simply extend the
-class. Extending a class is nearly identical to replacing a class with a
-couple exceptions:
+如果你所要做的只是在現存程式庫中加入一些功能，例如增加一兩個函數，那置換掉整個程式庫就太過火了。在這個狀況下，擴充類別是比較好的做法。擴充一個類別與用一些例外來取代一個類別幾乎是相同的： :
 
--  The class declaration must extend the parent class.
--  Your new class name and filename must be prefixed with MY\_ (this
-   item is configurable. See below.).
+-  類別宣告必須繼承（extend）父類別
+-  你的新類別名稱與檔名必須使用 MY\_ 前置字串（這是可設定的，請見下述）。
 
-For example, to extend the native Input class you'll create a file named
-application/core/MY_Input.php, and declare your class with::
+例如，要擴充一個內建的 Input 類別，你要先新增檔名為 application/core/MY_Input.php 的檔案，然後這樣宣告你的類別： ::
 
 	class MY_Input extends CI_Input {
 
 	}
 
-.. note:: If you need to use a constructor in your class make sure you
-	extend the parent constructor::
+.. note:: 如果你需要在你的類別中使用建構函數（Constructor），確定有在裡面擴充父類別的建構函數（Constructor）：
+
+::
 
 		class MY_Input extends CI_Input {
 
@@ -86,13 +71,9 @@ application/core/MY_Input.php, and declare your class with::
 			}
 		}
 
-**Tip:** Any functions in your class that are named identically to the
-methods in the parent class will be used instead of the native ones
-(this is known as "method overriding"). This allows you to substantially
-alter the CodeIgniter core.
+**Tip:**  你類別中任何與父類別中相同名稱的函數，將會取代父類別的（這一般叫做“方法覆蓋 method overriding”）。這個方式允許你實質上改變 CodeIgniter 的核心。
 
-If you are extending the Controller core class, then be sure to extend
-your new class in your application controller's constructors.
+如果你要擴充控制器（Controller）核心類別，請確定有在你的應用程式控制器（Controller）的建構函數（Constructor）中擴充你的新類別。
 
 ::
 
@@ -109,13 +90,11 @@ your new class in your application controller's constructors.
 		}
 	}
 
-Setting Your Own Prefix
+自訂子類別的前綴字串
 -----------------------
 
-To set your own sub-class prefix, open your
-*application/config/config.php* file and look for this item::
+要設定你自己的子類別前置字串，請編輯你的 *application/config/config.php* 檔案並修改下面的項目： ::
 
 	$config['subclass_prefix'] = 'MY_';
 
-Please note that all native CodeIgniter libraries are prefixed
-with CI\_ so DO NOT use that as your prefix.
\ No newline at end of file
+請注意，所有的 CodeIgniter 內建程式庫都使用 CI\_ 前綴字串，所以不要用它來當作你自己的前綴字串。