A Service runs in background to perform long-running operations or to perform work for remote processes. A service does not provide any user interface it runs only in background with User’s input. For example a service can play music in the background while the user is in a different App, or it might download data from the internet without blocking user’s interaction with the Android device.
If you have not defined your service in your AndroidManifest.xml, you will receive a
ServiceNotFoundException when attempting to start it.
For info on
IntentService, see here: http://stackoverflow.com/documentation/android/5319/intentservice#t=201610241904035833932