Netscape has proprietary rights to JavaScript, as it was first used in Netscape browsers. But basically, the language and its methods are somewhat simplified variations derived from existing application programming interfaces ( APIs ) such as C++.

And for any technology to be implemented successfully on the Web, it has to be adapted to work across multiple platforms. To expand JavaScript's interoperability with other systems, an international standards association for information and communication systems called ECMA ( the European Computer Manufacturers Association ), has initiated a working arrangement with Netscape to deliver a standardized, international programming language based on core JavaScript.

The standardized version of JavaScript, called ECMAScript, behaves the same way in all applications that support this standard. Other companies can use this open standard language to develop their implementation of JavaScript.

The first version of the ECMA standard is documented in the ECMA-262 specification.

JScript^® is Microsoft's implementation of the ECMA 262 language specification. It is a full implementation, plus some enhancements that take advantage of capabilities of Microsoft Internet Explorer.

The ECMA specification does not describe the Document Object Model ( DOM ), which is being standardized by the World Wide Web Consortium ( W3C ).

JavaScript and JScript™ both are compatible with ECMA, while each include features that are not part of the ECMA specification.

If you write scripts using the ECMA standard, there is greater chance that the scripts will work on most browsers. If you use the added features of both which the ECMA standard does not support, you risk limiting its function only to browsers that understand it.

To simplify our discussions from hereon, we shall use the term JavaScript to refer to all versions, unless specifically noted.

JavaScript is not useful as a standalone language, but is designed for easy embedding in other products and applications, such as web browsers. Inside a host environment, JavaScript can be used to access the objects of its environment and provide programmatic control over them.

JavaScript requires much less programming skills than the Common Gateway Interface ( CGI ). Unlike CGI, this tool can provide output on a document without needing administrative access to a Web server, which is usually reserved only for system administrators and webmasters who run the host machine.

But also unlike full-fledged programming languages, JavaScript works only within the browser on a user's system, and can access only objects currently stored in the computer's dynamic memory.

JavaScript cannot write information to any file on the user's computer or on the server, so no information generated by the script, or the user's interaction with it, can be saved for later use, except for cookies which are not discussed here.

JavaScript can "write" HTML in a sense, but only to what is made available to it.

JavaScript cannot manipulate any peripheral devices or access any program outside of the browser.

Still, JavaScript offers a simple, powerful means to enhance any Web site.