Android Support Library包是一個代碼庫的集合，這個集合提供Android framework API的向下兼容版本，並提供原本只通過庫（譯者注：這個庫指新版本的庫）的API才能使用的功能。每一個Support Library是針對一個特定的Android API級別向下兼容的。這種設計意味著你的應用可以使用庫（譯者注：這個庫指新版本的庫）的功能，並且可以和運行Android1.6（API level 4）或以上版本的設備兼容。

原文：The Android Support Library package is a set of code libraries that provide backward-compatible versions of Android framework APIs as well as features that are only available through the library APIs. Each Support Library is backward-compatible to a specific Android API level. This design means that your applications can use the libraries' features and still be compatible with devices running Android 1.6 (API level 4) and up.

這個指南提供了一些信息，這些信息包括利用Support Library可以使用哪些功能，如何在你的開發環境中使用這些功能，以及庫的發布管理。

原文：This guide provides information about what features are enabled by the Support Libraries, how to use them in your development environment and information about library releases.

概述

對於應用開發者來說，在Android項目中引入Support Library是一種最佳做法，這依賴於你的應用設置的目標平台版本的范圍和它用到的API。利用庫提供的功能可以幫助你提升應用的外觀，提升系統性能並擴大應用的用戶使用范圍。如果你使用了Android code template（代碼模板）工具，你會注意到所有的應用模板默認包含了一個或多個Support Library。

原文：Including the Support Libraries in your Android project is considered a best practice for application developers, depending on the range of platform versions your app is targeting and the APIs that it uses. Using the features the libraries provide can help you improve the look of your application, increase performance and broaden the reach of your application to more users. If you use the Android code template tools, you will notice that all the Android application templates include one or more of the Support Libraries by default.

每一個Support Library設定了一個目標的基礎Android API級別，並且提供了不通的功能集合。為了高效地使用這些庫，需要著重考慮一下你想使用哪些功能，並且理解每一個庫在不同的Android API級別都支持哪些功能。開始前，回顧一下Support Library Features指南。然後，進入Support Library Setup主題學習一下如何將Support Library合並到你的應用。想要了解更多關於Support Library API的細節，查看API參考中的android.support包。

原文：The Support Libraries each target a base Android API level and each provides a different set of features. In order to effectively use the libraries, it is important to consider what features you want to support and understand what features are supported by each library at what Android API level. To get started, review the Support Library Features guide. After that, go to the Support Library Setup topic to learn how to incorporate the Support Libraries into your application. For more details about Support Library APIs, see the android.support packages in the API reference.

版本修訂

關於版本修訂可以查看這裡：http://developer.android.com/tools/support-library/index.html#revisions