Android Software stack contains linux kernel, native libraries (middleware), Android Runtime, Application Framework and Applications.
Linux kernel is responsible for device drivers, power management, resource access etc. OS tasks.
On the top of linux kernel, their are Native libraries such as WebKit, OpenGL, FreeType, SQLite, Media, C runtime library (libc) etc. Sqlite is Android local database. All the library functions of device is in this sections.
The WebKit library is responsible for browser support, SQLite is for database, FreeType for font support, Media for playing and recording audio and video formats.
The main Android API’s are UI (User Interface), telephony, resources, locations, Content Providers (data) and package managers.