While including PDA applications (address book, calendar, to-do lists, etc.) as well as telephone capabilities on newer models, the BlackBerry is primarily known for its ability to send and receive e-mail wherever it can access a wireless network of certain cellular phone carriers. It has a built-in QWERTY keyboard, optimized for “thumbing”, the use of only the thumbs to type. System navigation is primarily accomplished by a scroll ball in the middle of the device. __
