What is meant by bundle ID in android, What is its usage, And can two android apps have same bundle ID? if YES then why? and if NO then why
A bundle ID otherwise known as a package in Android is the unique identifier for all Android apps. It needs to be unique as when you upload it to Google Play it identifies and publishes your app using the package name as the unique app identification.
Really it is the only thing which is necessary to identify your app, and generally it has 3 parts:
com.example.testapp
Where example is generally the company/publishers name, and testapp is the appname.
You will not be able to upload an APK to the store which has the same package as another app already in the store.
Should you ever need to change the package name in Eclipse, do the following:
Right click project > Android Tools > Rename Application Package...