Terminal is a terminal emulator

Terminal emulator

A terminal emulator, terminal application, term, or tty for short, is a program that emulates a video terminal within some other display architecture....

 included in Apple's Mac OS X

Mac OS X

Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...

 operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

. It originated in Mac OS X's predecessors, NeXTSTEP

NEXTSTEP

NeXTSTEP was the object-oriented, multitasking operating system developed by NeXT Computer to run on its range of proprietary workstation computers, such as the NeXTcube...

 and OPENSTEP

OpenStep

OpenStep was an object-oriented application programming interface specification for an object-oriented operating system that used a non-NeXTSTEP operating system as its core, principally developed by NeXT with Sun Microsystems. OPENSTEP was a specific implementation of the OpenStep API developed...

, and allows the user to interact with the computer through a command line interface. By default it provides a bash shell, which allows the OS X user to visually interact with the system core. Terminal features include tabs

Tab (GUI)

In the area of graphical user interfaces , a tabbed document interface is one that allows multiple documents to be contained within a single window, using tabs as a navigational widget for switching between sets of documents...

and customization of styles such as fonts and colors.