Simple way to understand the difference between JavaScript, JScript, & ECMAScript

JavaScript is a prototype-based scripting language that is dynamic, weakly typed and was formalized in the ECMAScript language standard.

JScript is the Microsoft implementation of the ECMA 262 language specification (Source).

ECMAScript is the scripting language standardized by Ecma International and is widely used for client-side scripting on the web.

Here’s a good explanation.