ECMAScript is a scripting language, standardized by ECMA (European Computer Manufacturers Association) International in the ECMA-262 specification. The language is widely used on the web, and is often confused with JavaScript or JScript, the two major dialects from which ECMAScript was standardized.
As previously said, the ECMA Standard is based on several originating technologies, the most well known being JavaScript (Netscape) and JScript (Microsoft). The language was invented by Brendan Eich at Netscape and first appeared in that company’s Navigator 2.0 browser. It has appeared in all subsequent browsers from Netscape and in all browsers from Microsoft starting with Internet Explorer 3.0.
These days all major browsers support this standard which was in Edition 3 at the time of this post. Due to the origin of ECMAScript Language this specification is usefull for all developers incorporating JavaScript to their projects. But you should always keep in your minds some differences between JavaScript and ECMAScript and check its interpretation in all browsers and platforms before you release your code to the public.