An open specification for seamless wireless short-range communications of data and voice between both mobile and stationary devices. For instance, it specifies how mobile phones, computers and PDAs interconnect with each other, with computers, and with office or home phones. The first generation of Bluetooth permits exchange of data up to a rate of 1 Mbps per second, even in areas with much electromagnetic disturbance. It transmits and receives via a short-range radio link using a globally available frequency band (2.4 GHz ISM band).

This is the handler for a global event - a trigger which fires in response to things like an incoming SMS, timer or even keypresses. Your code defines these handlers then can quit - Android registers them and will start yourapp should any fire.

A general purpose class to hold and manage disparate data types. Many java programmers end up using some kind of self-developed "utility" class to convert data types, manage their persistence and so on. This is the Android version which saves developers reinventing the wheel once again. It is keyed, so you can manage data using indexes with appropriate get() and put() methods.