A scripting language is used to write scripts. These contain a series of commands that are interpreted one by one at runtime unlike programming languages that are compiled first before running.
Nowadays, scripts are generally associated with web development where they are widely used to make dynamic web applications. Scripting languages can be divided into two categories:
Server-side scripting languages create the scripts that run on the server and hence minimize the workload of a browser. The functionality of your website is written in those scripting languages. The most commonly used server-side scripting languages are Perl, Ruby, Python, PHP, etc.
Client-side scripting languages create the scripts that run on the client side (i.e. your browser). These are sent from the server by server-side scripts. Some good examples are JavaScript, jQuery, CSS etc.