### Terminology: T3 and TADS 3

TADS 3 is a new version of the Text Adventure Development System. TADS 3 consists of a compiler for the TADS 3 programming language, code libraries that implement common functions and object classes for adventure games, and interpreter applications that execute games and provide a user interface. The interpreter applications provide a set of intrinsic functions that a game program can call to interact with the user interface, among other things.

T3 is a "virtual machine," or VM, which is an abstract computer. A virtual machine in many ways resembles an actual computer: it has a set of programming instructions, data registers, memory, and other features that most computers have. A VM doesn't usually exist as an actual computer, though, because a VM's specification describes only how the machine behaves, not how to build the electronics necessary for a physical version of the machine; however, a software emulator for the VM can be created, and this software emulator can run on real computers.

The TADS 3 interpreters are implemented on top of a T3 VM emulator. The T3 VM provides mechanisms by which a program executing on the VM can access functionality provided by the host environment; the TADS 3 interpreters use these mechanisms to provide user interface services and other functions to TADS 3 programs.