Android is open source Linux based OS. This Linux-based software stack divided into five sections and four Layers as shown in the below Image.
1.Linux Kernel :Linux kernel exists at the root of android architecture. It manage all device drivers(like Audio,Binder,Display,Keypad,Bluetooth,Camera,USB,WIFI etc.) ,
Power Management ,Device management, Memory Management etc. Linux kernel is bottom layer in android Architecture.
2.Libraries :On the top of Linux kernel there are native libraries which includes SQLite, Libc, OpenGL, Webkit , Media etc.
SQLite is a light weight database for Android, Webkit is for browser support, Media is for audio video support.
3.Android Runtime: This section is available on Second Layer and third Section of Android Architecture. This section provides very important component i.e. DVM(Dalvik Virtual Machine)
Its like JVM(Java Virtual Machine) . DVM is designed and optimized for Android. It consume less memory and light weighted.
4. Android Framework: Third Layer and fourth section of Android Architecture is Android Framework. The Android Framework includes thefollowing Building Blocks of Android Application which are required for develop an App : Activity Manager, Content Providers , Resource Manager, Notification Manager, View System.
5.Applications: Last Layer of Android Architecture is Application, You will find all Applications at this Layer. Android Comes with core Apps like Contacts, SMS Messaging , Calendars, Browser, Email etc.