It is a set of complete software programming for mobile device. They are computers, phone, and electronic etc. ANDROID has based on Linux-based software. key mobile applications and middle ware. It can known as mobile operating systems. This is not belonging to the mobile operating systems. Now a days it used in different devices. They are mobiles, Smartphone, tablets, and computers.


Before discussing about this topics we have to know WHAT IS ANDROID. This is a packaging of software technologies. It based on Linux operating systems for mobiles. Such as computers, Smartphone, tablets, and mobiles. It developed through Google and after it generated by Open Handset Alliances(OHA). This code can written by Java and also other languages also used. Android projects can create real world as successful product. It is main goal of android technology. This develops the end users mobile experience. Android codes are having many names. They are Kitkat, lollypop, Jelly Bean, Ice cream Sandwich, Froyo, Éclair, and Donut etc.
After knowing about android, we have to learn features on it. There given below
1. Everyone can operating platform.
2. Consumers are having so many mobile applications in software.
3. It is open source technology.
4. It offers many exiting features. Like as opening screen, live RSS feed, another details etc.
It offers for support messaging offers, storage, Media layout, and web browsers etc.

Categories of Android applications:

In market there are many android applications used. They given below:
Communication Media and Video
Music and Audio
Travel and Local
Media and Video

Android Service:

which used to perform tasks or operations and to do background work. They are handle network transactions and playing music. The operations are running even if the data destroyed. And service can enclosed by the component. To do tasks and IPC( Inter Process Communication).
 Life cycle on this program:
The life cycle on this can follow two different ways: they are
1. Started
2. Bound
1) Started Service:
Start service method activated then component service started. Now the background work runs forever. When stop service method used then the service stopped. The stop service will stop by calling the stop self method.
2) Bound Service:
Another components are using to call bind service method the service is bound. If calling the unbind service method the client will be unbind. If all clients are unbind then also the service cannot stopped.
Web service:
This application creation is not a big task. We can create web service application. Web service application creation in android is not a difficult task. Relaxed web service application creation is very easy. Information saved in external database. They are oracle, posture sql, sql server and mysql.
Core building blocks:
Fundamental components  or core building blocks are
· view
· service
· content provider
· fragments
· activities
· intents
· mainfest.xml.