The Microsoft Script Editor (MSE or MSE.EXE or "C:\Program Files\Microsoft Office\OFFICE11\mse7.exe" in Office 2003) is an optional tool included in Microsoft Office 2000

Microsoft Office

Microsoft Office is a non-free commercial office suite of inter-related desktop applications, servers and services for the Microsoft Windows and Mac OS X operating systems, introduced by Microsoft in August 1, 1989. Initially a marketing term for a bundled set of applications, the first version of...

 through Office 2003 as well newer versions of office and is found in "C:\Program Files\common files" directory.

It allows one to work with HTML

HTML

HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....

 code, DHTML

Dynamic HTML

Dynamic HTML, or DHTML, is an umbrella term for a collection of technologies used together to create interactive and animated web sites by using a combination of a static markup language , a client-side scripting language , a presentation definition language , and the Document Object Model.DHTML...

 objects, and script

Scripting language

A scripting language, script language, or extension language is a programming language that allows control of one or more applications. "Scripts" are distinct from the core code of the application, as they are usually written in a different language and are often created or at least modified by the...

 in an Office document

Office suite

In computing, an office suite, sometimes called an office software suite or productivity suite is a collection of programs intended to be used by knowledge workers...

 from within an Office application. In addition to this, if installed, Internet Explorer will allow one to debug JavaScript

JavaScript

JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....

 and VBScript

VBScript

VBScript is an Active Scripting language developed by Microsoft that is modeled on Visual Basic. It is designed as a “lightweight” language with a fast interpreter for use in a wide variety of Microsoft environments...

 with the editor if the "Disable Script Debugging" Internet Explorer

Internet Explorer

Windows Internet Explorer is a series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems, starting in 1995. It was first released as part of the add-on package Plus! for Windows 95 that year...

preference option is not checked.

In the About Box, it calls itself "Microsoft Development Environment 7.0". It is a trimmed down version of Visual Studio .NET 2002 (7.0)'s IDE.