Terminal

Terminal (also referred to as Terminal.app) is a terminal emulator included in Apple's Mac OS X operating system. It originated in Mac OS X's predecessors, NEXTSTEP and OPENSTEP, and allows the user to interact with the computer through a command line interface. On Mac OS X, Terminal is located in the folder. When started, Terminal typically initiates a login session with a Unix shell. In versions of Mac OS X since 10.3 "Panther", the default shell is bash; prior to 10.3 the default shell was tcsh. As of 10.4 "Tiger", Mac OS X provides zsh and ksh in addition to bash and tcsh. Prior to Mac OS X 10.5 "Leopard", the Terminal did not set by default the DISPLAY environment variable read by UNIX programs that make use of X Window System GUI. Setting it permits one to launch X11 applications (provided Apple's X11.app, available as an optional package on the installation DVD, has been installed and launched). In 10.5, the Terminal does set this variable, allowing X11 applications to be... full article at wikipedia