Client Side JavaScript (CSJS) is an extended version of JavaScript that enables the enhancement and manipulation of web pages and client browsers. In a browser environment, your code will have access to things provided only by the browser, like the document object for the current page, the window, functions like alert that pop up a message, etc. The main tasks of Client-side JavaScript are validating input, animation, manipulating UI elements, and applying styles, some calculations are done when you don't want the page to refresh so often. In web developing it's the browser, in the user's machine, that runs this code, and is mainly done in javascript. Also, this code must run in a variety of browsers.

Client Side JavaScript (CSJS) is an extended version of **JavaScript** that enables the enhancement and manipulation of web pages and client browsers. In a **browser environment**, your code will have access to things provided only by the browser, like the document object for the current page, the window, functions like alert that pop up a message, etc. The main tasks of **Client-side JavaScript** are validating input, animation, manipulating UI elements, and applying styles, some calculations are done when you don't want the page to refresh so often. In web developing it's the browser, in the user's machine, that runs this code, and is mainly done in **javascript**. Also, this code must run in a variety of browsers.