what is BroadcastReceiver? and how I use BroadcastReceiver to receiver message through to DDMS to Eclipse

http://code.google.com/android/reference/android/content/BroadcastReceiver.html
A broadcast receiver is used for receiving Intents which are being broadcasted. Like the BOOT_COMPLETED intent, it gets broadcasted to all the BroadcastReceivers which have been registered for receiving BOOT_COMPLETED. Using this BroadcastReceiver you can then do something when BOOT_COMPLETED gets broadcasted.