This layer and the layer above it are written completely in Java. The applications framework provides all of the major APIs that the applications will use including things like sharing data, accessing the telephony system, and receiving notifications. An important thing to note about Android OS is that all applications use this same framework no matter the author of the application. This is quite a departure from what many other mobile OS designers have chosen to do. For instance the iPhone most certainly differentiates between Apple software and third-party software down to the copy-and-paste feature