JavaScript, often abbreviated JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. Over 97% of websites use JavaScript on the client side for web page behavior, often incorporating third-party libraries.

Key differences between Java and JavaScript: Java is an OOP programming language while Java Script is an OOP scripting language. Java creates applications that run in a virtual machine or browser while JavaScript code is run on a browser only. Java code needs to be compiled while JavaScript code are all in text.

You do not need to know Java to learn JavaScript. Despite their names, the two languages have very little in common and are used for completely different areas of development. You can learn either language first but learning Java is not a prerequisite to picking up JavaScript

JavaScript is a general-purpose scripting language that conforms to the ECMAScript specification. The ECMAScript specification is a blueprint for creating a scripting language. JavaScript is an implementation of that blueprint. On the whole, JavaScript implements the ECMAScript specification as described in ECMA-262.