Developer:Various (mostly Google and the Open Handset Alliance)
Written In:Java (UI), C (core), C++
OS FamilyUnix-like (modified Linux kernel)
Android is an open-sourced operating system that is used on mobile devices, such as mobiles and tablets. The Android application executes within its own process and its own instance of Dalvik Virtual Machine(DVM) or Android RunTime(ART).
Service is an application component that facilitates an application to run in the background in order to perform long-running operations without user interaction. A service can run continuously in the background even if the application is closed or even after the user switches to another application.
An adapter in Android acts as a bridge between an AdapterView and the underlying data for that view. The adapter holds the data and sends the data to the adapter view, the view can take the data from the adapter view and shows the data on different views like a spinner, list view, grid view, etc
Bundles are used to pass the required data between various Android activities. These are like HashMap that can take trivial data types. Below code shows how to transfer a piece of data by using bundle: