Starting Up with Javascript

What is a Client Side Scripting?
The Scripts that run on a Client Side Machine, the scripts that never ping Server in order to run is called Client Side Scripting. JavaScript is one of the Client Side Scripting Languages.

What is the use of Client Side Scripting?
Certain Validations like "Checking If New Password & Confirm Password Matches","Checking if Date of Birth Matches our Criteria" etc., Not only such validations, we can also "Create an image gallery either in a HTML page or in a blogs post."

How does a JavaScript code look like?
<script type='text/javascript'>
---Script Code here---