번역 : jameroid.tistory.com
분류 : Android Basics
출처 : http://developer.android.com/guide/basics/what-is-android.html

Libraries

Android includes a set of C/C++ libraries used by various components of the Android system. These capabilities are exposed to developers through the Android application framework. Some of the core libraries are listed below:

• System C library - a BSD-derived implementation of the standard C system library (libc), tuned for embedded Linux-based devices
• Media Libraries - based on PacketVideo's OpenCORE; the libraries support playback and recording of many popular audio and video formats, as well as static image files, including MPEG4, H.264, MP3, AAC, AMR, JPG, and PNG
• Surface Manager - manages access to the display subsystem and seamlessly composites 2D and 3D graphic layers from multiple applications
• LibWebCore - a modern web browser engine which powers both the Android browser and an embeddable web view
• SGL - the underlying 2D graphics engine
• 3D libraries - an implementation based on OpenGL ES 1.0 APIs; the libraries use either hardware 3D acceleration (where available) or the included, highly optimized 3D software rasterizer
• FreeType - bitmap and vector font rendering
• SQLite - a powerful and lightweight relational database engine available to all applications

What is Android?

Android is a software stack for mobile devices that includes an operating system, middleware and key applications. The Android SDK provides the tools and APIs necessary to begin developing applications on the Android platform using the Java programming language.

특징들
- 어플리케이션 프레임웍 :  컴포턴트의 교체와 재새용을 가능하게 한다.
- 달빅 가상 머신 : 모바일 디바이스을 위해 최적화 되었다.
- 내장된 브라우저 : 공개소스 WebKit 엔진을 기초로 한다.
- 최적화된 그래픽 : 맞춤 2D 그래픽 라이브, OpenGL ES1.0 규격을 기초한 3D그래픽으로 로 강해졌다.
- SQLite : 구조적 데이타 저장을 위해
- 미디어 지원 : 오디오, 비디오 그리고 정지 이미지 포맷  (MPEG4, H.264, MP3, AAC, JPG, PNG, GIF)
- (하드웨어 의존) GSM 기술
- (하드웨어 의존) 블루투스, EDGE, 3G 와 WiFI
- (하드웨어 의존) 카메라, GPS, 나침반(compass) 그리고 가속도계(accelerometer)
- 풍부한 개발 환경 : 디바이스 에뮬레이터(장비모방),디버그 툴, 메모리와 성능 분석(performance profiling)
                          그리고 이클립스 IDE를 위한 플러그인 을 포함한다.

Features

• Application framework enabling reuse and replacement of components
• Dalvik virtual machine optimized for mobile devices
• Integrated browser based on the open source WebKit engine
• Optimized graphics powered by a custom 2D graphics library; 3D graphics based on the OpenGL ES 1.0 specification (hardware acceleration optional)
• SQLite for structured data storage
• Media support for common audio, video, and still image formats (MPEG4, H.264, MP3, AAC, AMR, JPG, PNG, GIF)
• GSM Telephony (hardware dependent)
• Bluetooth, EDGE, 3G, and WiFi (hardware dependent)
• Camera, GPS, compass, and accelerometer (hardware dependent)
• Rich development environment including a device emulator, tools for debugging, memory and performance profiling, and a plugin for the Eclipse IDE

안드로이드 아키텍쳐
  : 아래 그림도료는 안드로이드 운영시스텝ㅁ의 주요 구성품(컴포턴트)을 보여준다

Applications

Android will ship with a set of core applications including an email client, SMS program, calendar, maps, browser, contacts, and others. All applications are written using the Java programming language.

Application Framework

By providing an open development platform, Android offers developers the ability to build extremely rich and innovative applications. Developers are free to take advantage of the device hardware, access location information, run background services, set alarms, add notifications to the status bar, and much, much more.

Developers have full access to the same framework APIs used by the core applications. The application architecture is designed to simplify the reuse of components; any application can publish its capabilities and any other application may then make use of those capabilities (subject to security constraints enforced by the framework). This same mechanism allows components to be replaced by the user.

Underlying all applications is a set of services and systems, including:

• A rich and extensible set of Views that can be used to build an application, including lists, grids, text boxes, buttons, and even an embeddable web browser
• Content Providers that enable applications to access data from other applications (such as Contacts), or to share their own data
• A Resource Manager, providing access to non-code resources such as localized strings, graphics, and layout files
• A Notification Manager that enables all applications to display custom alerts in the status bar
• An Activity Manager that manages the lifecycle of applications and provides a common navigation backstack

For more details and a walkthrough of an application, see the Notepad Tutorial.