The BattleTag is a player-created name that serves as your Battle.net title. It is used in all Blizzard games, as well as on their forums and community websites. Players create a name of up to 12 characters, and this becomes their official title on Battle.net. Your BattleTag is what other players see on your Diablo III characters, and what appears on their Friends List.
A digital camera records and stores photographic images in digital form. Many current models are also able to capture sound or video, in addition to still images.
Digital cameras use a light-sensitive chip rather than film to capture an image. The camera is designed to let light through a hole (aperture) on to the chip for a limited amount of time (exposure). Digital cameras use auto exposure to take care of exposing the picture for you.